diff --git a/.gitignore b/.gitignore
index 510c73d..b02d695 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,114 +1,446 @@
-# Byte-compiled / optimized / DLL files
-__pycache__/
-*.py[cod]
-*$py.class
+## Ignore Visual Studio temporary files, build results, and
+## files generated by popular Visual Studio add-ons.
+
+# User-specific files
+*.suo
+*.user
+*.userosscache
+*.sln.docstates
 
-# C extensions
-*.so
+# User-specific files (MonoDevelop/Xamarin Studio)
+*.userprefs
 
-# Distribution / packaging
-.Python
+# Build results
+[Dd]ebug/
+[Dd]ebugPublic/
+[Rr]elease/
+[Rr]eleases/
+x64/
+x86/
 build/
-develop-eggs/
-dist/
-downloads/
-eggs/
-.eggs/
-lib/
-lib64/
-parts/
-sdist/
-var/
-wheels/
-*.egg-info/
-.installed.cfg
-*.egg
-MANIFEST
-
-# PyInstaller
-#  Usually these files are written by a python script from a template
-#  before PyInstaller builds the exe, so as to inject date/other infos into it.
-*.manifest
-*.spec
-
-# Installer logs
-pip-log.txt
-pip-delete-this-directory.txt
-
-# Unit test / coverage reports
-htmlcov/
-.tox/
-.nox/
-.coverage
-.coverage.*
-.cache
-nosetests.xml
-coverage.xml
-*.cover
-.hypothesis/
-.pytest_cache/
-
-# Translations
-*.mo
-*.pot
-
-# Django stuff:
+bld/
+[Bb]in/
+[Oo]bj/
+out/
+
+# Visual Studio 2015 cache/options directory
+.vs/
+# Uncomment if you have tasks that create the project's static files in wwwroot
+#wwwroot/
+
+# MSTest test Results
+[Tt]est[Rr]esult*/
+[Bb]uild[Ll]og.*
+
+# NUNIT
+*.VisualState.xml
+TestResult.xml
+
+# Build Results of an ATL Project
+[Dd]ebugPS/
+[Rr]eleasePS/
+dlldata.c
+
+# Benchmark Results
+BenchmarkDotNet.Artifacts/
+
+# .NET Core
+project.lock.json
+project.fragment.lock.json
+artifacts/
+**/Properties/launchSettings.json
+# DNX
+project.lock.json
+artifacts/
+
+*_i.c
+*_p.c
+*_i.h
+*.ilk
+*.meta
+*.obj
+*.pch
+*.pdb
+*.pgc
+*.pgd
+*.rsp
+*.sbr
+*.tlb
+*.tli
+*.tlh
+*.tmp
+*.tmp_proj
 *.log
-local_settings.py
-db.sqlite3
+*.vspscc
+*.vssscc
+.builds
+*.pidb
+*.svclog
+*.scc
+
+# Chutzpah Test files
+_Chutzpah*
+
+# Visual C++ cache files
+ipch/
+*.aps
+*.ncb
+*.opendb
+*.opensdf
+*.sdf
+*.cachefile
+*.VC.db
+*.VC.VC.opendb
+*.opensdf
+*.sdf
+*.cachefile
+
+# Visual Studio profiler
+*.psess
+*.vsp
+*.vspx
+*.sap
+
+# Visual Studio Trace Files
+*.e2e
+
+# TFS 2012 Local Workspace
+$tf/
+
+# Guidance Automation Toolkit
+*.gpState
+
+# ReSharper is a .NET coding add-in
+_ReSharper*/
+*.[Rr]e[Ss]harper
+*.DotSettings.user
+
+# JustCode is a .NET coding add-in
+.JustCode
+
+# TeamCity is a build add-in
+_TeamCity*
+
+# DotCover is a Code Coverage Tool
+*.dotCover
+
+# AxoCover is a Code Coverage Tool
+.axoCover/*
+!.axoCover/settings.json
+
+# Visual Studio code coverage results
+*.coverage
+*.coveragexml
+
+# NCrunch
+_NCrunch_*
+.*crunch*.local.xml
+nCrunchTemp_*
+
+# MightyMoose
+*.mm.*
+AutoTest.Net/
+
+# Web workbench (sass)
+.sass-cache/
+
+# Installshield output folder
+[Ee]xpress/
+
+# DocProject is a documentation generator add-in
+DocProject/buildhelp/
+DocProject/Help/*.HxT
+DocProject/Help/*.HxC
+DocProject/Help/*.hhc
+DocProject/Help/*.hhk
+DocProject/Help/*.hhp
+DocProject/Help/Html2
+DocProject/Help/html
 
-# Flask stuff:
-instance/
-.webassets-cache
+# Click-Once directory
+# publish/
 
-# Scrapy stuff:
-.scrapy
+# Publish Web Output
+*.azurePubxml
+# TODO: Comment the next line if you want to checkin your web deploy settings 
+# but database connection strings (with potential passwords) will be unencrypted
+*.pubxml
+*.publishproj
 
-# Sphinx documentation
-docs/_build/
+# NuGet Packages
+*.nupkg
+# The packages folder can be ignored because of Package Restore
+**/packages/*
+# except build/, which is used as an MSBuild target.
+!**/packages/build/
+# Uncomment if necessary however generally it will be regenerated when needed
+#!**/packages/repositories.config
 
-# PyBuilder
-target/
+# Windows Azure Build Output
+csx/
+*.build.csdef
 
-# Jupyter Notebook
-.ipynb_checkpoints
+# Windows Store app package directory
+AppPackages/
 
-# IPython
-profile_default/
-ipython_config.py
+# Visual Studio cache files
+# files ending in .cache can be ignored
+*.[Cc]ache
+# but keep track of directories ending in .cache
+!*.[Cc]ache/
 
-# pyenv
-.python-version
+# Others
+ClientBin/
+[Ss]tyle[Cc]op.*
+~$*
+*~
+*.dbmdl
+*.dbproj.schemaview
+*.jfm
+*.pfx
+*.publishsettings
+orleans.codegen.cs
 
-# celery beat schedule file
-celerybeat-schedule
+# Since there are multiple workflows, uncomment next line to ignore bower_components
+# (https://github.com/github/gitignore/pull/1529#issuecomment-104372622)
+#bower_components/
 
-# SageMath parsed files
-*.sage.py
+*.pfx
+*.publishsettings
+node_modules/
+orleans.codegen.cs
 
-# Environments
-.env
-.venv
-env/
-venv/
-ENV/
-env.bak/
-venv.bak/
+# RIA/Silverlight projects
+Generated_Code/
 
-# Spyder project settings
-.spyderproject
-.spyproject
+# Backup & report files from converting an old project file
+# to a newer Visual Studio version. Backup files are not needed,
+# because we have git ;-)
+_UpgradeReport_Files/
+Backup*/
+UpgradeLog*.XML
+UpgradeLog*.htm
 
-# Rope project settings
-.ropeproject
+# SQL Server files
+*.mdf
+*.ldf
+*.ndf
 
-# mkdocs documentation
-/site
+# Business Intelligence projects
+*.rdl.data
+*.bim.layout
+*.bim_*.settings
+
+# Microsoft Fakes
+FakesAssemblies/
+
+# GhostDoc plugin setting file
+*.GhostDoc.xml
+
+# Node.js Tools for Visual Studio
+.ntvs_analysis.dat
+node_modules/
+
+# Typescript v1 declaration files
+typings/
+# Node.js Tools for Visual Studio
+.ntvs_analysis.dat
+
+# Visual Studio 6 build log
+*.plg
+
+# Visual Studio 6 workspace options file
+*.opt
+
+# Visual Studio 6 auto-generated workspace file (contains which files were open etc.)
+*.vbw
+
+# Visual Studio LightSwitch build output
+**/*.HTMLClient/GeneratedArtifacts
+**/*.DesktopClient/GeneratedArtifacts
+**/*.DesktopClient/ModelManifest.xml
+**/*.Server/GeneratedArtifacts
+**/*.Server/ModelManifest.xml
+_Pvt_Extensions
+
+# Paket dependency manager
+.paket/paket.exe
+paket-files/
+
+# FAKE - F# Make
+.fake/
+
+# JetBrains Rider
+.idea/
+*.sln.iml
+
+# CodeRush
+.cr/
+
+# Python Tools for Visual Studio (PTVS)
+__pycache__/
+*.pyc
+
+# Cake - Uncomment if you are using it
+# tools/**
+# !tools/packages.config
+
+# Tabs Studio
+*.tss
+
+# Telerik's JustMock configuration file
+*.jmconfig
+
+# BizTalk build output
+*.btp.cs
+*.btm.cs
+*.odx.cs
+*.xsd.cs
+
+# OpenCover UI analysis results
+OpenCover/
+
+/build
+/Build
+/deploy
+/package
+bin/
+obj/
+sql/
+*/obj/debug
+**/Debug
+#ignore thumbnails created by windows
+Thumbs.db
+#Ignore files build by Visual Studio
+*.obj
+*.pdb
+*.user
+*.aps
+*.pch
+*.docstates
+*.vspscc
+*_i.c
+*_p.c
+*.ncb
+*.suo
+*.tlb
+*.dbmdl
+*.schemaview
+*.tlh
+*.cache
+*.ilk
+*.log
+[Bb]in
+[Dd]ebug*/
+*.lib
+*.sbr
+obj/
+[Rr]elease*/
+_ReSharper*/
+[Tt]est[Rr]esult*
+*.docstates
+*.swp
+*.*~
+*.gpState
+*.ReSharper*
+*.preflight
+*.nocommit
+#Ignore Recovery Files made by Excel
+~$*.xlsx
+*.rdl.data
+
+*.jfm
+
+#======================================================================================
+# The below section could possibly be removed as these should be ignored by the above.
+#======================================================================================
+
+samples/in-memory/ticket-reservations/DemoWorkload/obj/Debug/TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs
+*.nupkg
+samples/in-memory/ticket-reservations/packages/CircularGauge.1.0.0/CreatePackageFile.bat
+*.suo
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/bin/Debug/PopulateAlwaysEncryptedData.exe
+*.pdb
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/bin/Debug/PopulateAlwaysEncryptedData.vshost.exe
+*.Cache
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/bin/Debug/PopulateAlwaysEncryptedData.exe.config
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/obj/Debug/TemporaryGeneratedFile_036C0B5B-1481-4323-8D20-8F5ADCB23D92.cs
+samples/databases/wide-world-importers/workload-drivers/vehicle-location-insert/MultithreadedInMemoryTableInsert/obj/Debug/TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs
+*.exe
+samples/features/in-memory/iot-smart-grid/ConsoleClient/bin/Release/DataGenerator.dll
+samples/features/in-memory/iot-smart-grid/ConsoleClient/bin/Release/Reports/PowerDashboard.pbix
+samples/databases/wide-world-importers/wwi-integration-etl/Daily ETL/bin/Development/Daily ETL.ispac
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/obj/Release/PopulateAlwaysEncryptedData.csproj.FileListAbsolute.txt
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/bin/Release/PopulateAlwaysEncryptedData.vshost.exe.config
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/obj/Release/TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs
+*.dll
+samples/features/in-memory/ticket-reservations/DemoWorkload/obj/Release/DemoWorkload.FrmConfig.resources
+samples/features/in-memory/ticket-reservations/DemoWorkload/bin/Release/DemoWorkload.vshost.exe.config
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/obj/Debug/PopulateAlwaysEncryptedData.csproj.FileListAbsolute.txt
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/bin/Debug/PopulateAlwaysEncryptedData.vshost.exe.config
+*.zip
+samples/features/in-memory/ticket-reservations/packages/CircularGauge.1.0.0/CreatePackageFile.bat
+samples/features/in-memory/ticket-reservations/TicketReservations/TicketReservations.dbmdl
+samples/databases/wide-world-importers/workload-drivers/vehicle-location-insert/MultithreadedInMemoryTableInsert/obj/Release/TemporaryGeneratedFile_E7A71F73-0F8D-4B9B-B56E-8E70B10BC5D3.cs
+samples/databases/wide-world-importers/workload-drivers/vehicle-location-insert/MultithreadedInMemoryTableInsert/obj/Debug/MultithreadedInMemoryTableInsert.csproj.FileListAbsolute.txt
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/obj/Debug/PopulateAlwaysEncryptedData.Properties.Resources.resources
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/obj/Release/PopulateAlwaysEncryptedData.PopulateAlwaysEncryptedDataMain.resources
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/bin/Debug/PopulateAlwaysEncryptedData.vshost.exe.manifest
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/obj/Debug/PopulateAlwaysEncryptedData.PopulateAlwaysEncryptedDataMain.resources
+samples/databases/wide-world-importers/workload-drivers/vehicle-location-insert/MultithreadedInMemoryTableInsert/obj/Release/MultithreadedInMemoryTableInsert.Properties.Resources.resources
+samples/databases/wide-world-importers/sample-scripts/always-encrypted/PopulateAlwaysEncryptedData/obj/Release/PopulateAlwaysEncryptedData.Properties.Resources.resources
+samples/features/in-memory/ticket-reservations/packages/CircularGauge.1.0.0/ReadMe.txt
+*.dacpac
+samples/features/in-memory/ticket-reservations/TicketReservations/obj/Release/Model.xml
+samples/features/in-memory/ticket-reservations/DemoWorkload/obj/Debug/TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs
+*.dat
+
+*.user
+samples/features/in-memory/ticket-reservations/DemoWorkload/obj/Release/TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs
+samples/databases/wide-world-importers/workload-drivers/vehicle-location-insert/MultithreadedInMemoryTableInsert/obj/Debug/TemporaryGeneratedFile_E7A71F73-0F8D-4B9B-B56E-8E70B10BC5D3.cs
+samples/features/in-memory/ticket-reservations/DemoWorkload/bin/Debug/DemoWorkload.vshost.exe.config
+samples/features/in-memory/ticket-reservations/DemoWorkload/obj/Release/DemoWorkload.Properties.Resources.resources
+samples/databases/wide-world-importers/wwi-integration-etl/Daily ETL/obj/Development/Project.params
+samples/features/in-memory/ticket-reservations/DemoWorkload/obj/Debug/DemoWorkload.csproj.FileListAbsolute.txt
+samples/features/in-memory/iot-smart-grid/Db/obj/Release/Model.xml
+samples/applications/iot-smart-grid/DataGenerator/obj/Debug/TemporaryGeneratedFile_036C0B5B-1481-4323-8D20-8F5ADCB23D92.cs
+samples/databases/wide-world-importers/workload-drivers/order-insert/MultithreadedOrderInsert/bin/Debug/MultithreadedOrderInsert.exe.config
+samples/features/in-memory/iot-smart-grid/ConsoleClient/bin/Release/ConsoleClient.exe.config
+*.jfm
+samples/features/in-memory/ticket-reservations/TicketReservations/bin/Release/TicketReservations.publish.sql
+samples/applications/iot-smart-grid/ConsoleClient/bin/Release/ConsoleClient.exe.config
+samples/applications/iot-smart-grid/Db/Db.dbmdl
+samples/databases/wide-world-importers/workload-drivers/order-insert/MultithreadedOrderInsert/obj/Release/TemporaryGeneratedFile_036C0B5B-1481-4323-8D20-8F5ADCB23D92.cs
+samples/databases/wide-world-importers/wwi-dw-ssdt/wwi-dw-ssdt/obj/Debug/Model.xml
+samples/databases/wide-world-importers/wwi-dw-ssdt/wwi-dw-ssdt/WideWorldImportersDW.dbmdl
+samples/features/in-memory/iot-smart-grid/WinFormsClient/bin/Release/Reports/PowerDashboard.pbix
+samples/databases/wide-world-importers/wwi-ssdt/wwi-ssdt/WideWorldImporters.dbmdl
+samples/databases/wide-world-importers/workload-drivers/order-insert/MultithreadedOrderInsert/obj/Debug/TemporaryGeneratedFile_E7A71F73-0F8D-4B9B-B56E-8E70B10BC5D3.cs
+samples/databases/wide-world-importers/wwi-ssasmd/wwi-ssasmd/bin/WWI-SSASMD.asdatabase
+samples/applications/iot-smart-grid/Db/obj/Release/Db.sqlproj.FileListAbsolute.txt
+*.manifest
+samples/applications/iot-smart-grid/WinFormsClient/obj/Debug/TemporaryGeneratedFile_036C0B5B-1481-4323-8D20-8F5ADCB23D92.cs
+samples/databases/wide-world-importers/wwi-ssasmd/wwi-ssasmd/obj/Development/IncrementalShapshot.xml
+samples/applications/iot-smart-grid/ConsoleClient/bin/Release/Reports/PowerDashboard.pbix
+samples/applications/iot-smart-grid/Db/obj/Release/Model.xml
+samples/databases/wide-world-importers/workload-drivers/order-insert/MultithreadedOrderInsert/obj/Release/MultithreadedOrderInsert.csproj.FileListAbsolute.txt
+samples/applications/iot-smart-grid/ConsoleClient/obj/Debug/TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs
+samples/applications/iot-smart-grid/WinFormsClient/bin/Release/Client.exe.config
+samples/databases/wide-world-importers/workload-drivers/order-insert/MultithreadedOrderInsert/bin/Release/MultithreadedOrderInsert.exe.config
+samples/databases/wide-world-importers/workload-drivers/order-insert/MultithreadedOrderInsert/obj/Debug/MultithreadedInMemoryTableInsert.MultithreadedOrderInsertMain.resources
+/samples/features/epm-framework/5.0/2Reporting/PolicyReports/PolicyEvaluationErrors.rdl.data
+/samples/features/epm-framework/5.0/2Reporting/PolicyReports/PolicyEvaluationErrorDetails.rdl.data
+/samples/features/epm-framework/5.0/2Reporting/PolicyReports/PolicyEvaluationDetails.rdl.data
+/samples/features/epm-framework/5.0/2Reporting/PolicyReports/PolicyDetails.rdl.data
+/samples/features/epm-framework/5.0/2Reporting/PolicyReports/PolicyDashboard.rdl.data
+/samples/features/epm-framework/5.0/2Reporting/PolicyReports/bin/Debug
+/samples/features/epm-framework/5.0/2Reporting/PolicyReports/PolicyDashboard - Backup.rdl
+/samples/features/epm-framework/5.0/2Reporting/PolicyReports/PolicyDashboardFiltered.rdl.data
+samples/features/sql-management-objects/src/out/CodeCoverage/CodeCoverage.config
 
-# mypy
-.mypy_cache/
-.dmypy.json
-dmypy.json
+# Certificates
+*.pem
+*.p12
 
-# Pyre type checker
-.pyre/
+# Composer
+/vendor/
\ No newline at end of file
diff --git a/README.md b/README.md
index 84b53db..529f7a5 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,17 @@
-# Algorithms
+# Lab-3 Discount program
+Task code: DISCNT
+
+The fashion store has started a seasonal sale, and offers customers a discount
+for every 3rd purchased product. You have chosen the goods you want to buy and want
+take advantage of this offer to save money as much as possible.
+Of course, the amount you have to pay depends on how much
+order you will buy the goods. Knowing the price of each product, as well as the percentage
+discounts, calculate the most advantageous amount for which you can buy all the goods.
+Input data
+The input file discnt .in consists of two lines.
+• The first line contains a list of integers from 0 to 1,000,000,000 inclusive, separated by a space - the prices of individual products you want to buy. The total number of goods is from 1 to 10,000.
+• The second line contains a discount - an integer from 0 to 100 inclusive, which means the percentage of the discount for every third product.
+
+Imprint
+The source discnt .out file must contain one number - the minimum amount that must be spent to purchase all products. The number must always have two fractional signs, and be rounded to the second decimal place.
  
diff --git a/discount.in b/discount.in
new file mode 100644
index 0000000..12c6f56
--- /dev/null
+++ b/discount.in
@@ -0,0 +1,2 @@
+1 2 3 4 5 6 7 
+100
\ No newline at end of file
diff --git a/discount.out b/discount.out
new file mode 100644
index 0000000..3d3be3c
--- /dev/null
+++ b/discount.out
@@ -0,0 +1 @@
+15.0
\ No newline at end of file
diff --git a/main.py b/main.py
new file mode 100644
index 0000000..2a3346a
--- /dev/null
+++ b/main.py
@@ -0,0 +1,42 @@
+def count_discount():
+    input_prices = open_file("discount.in")
+    discount_pers = (input_prices.pop(-1) / 100)
+    final_sum = sum(sort_prices(input_prices, discount_pers))
+    return round(final_sum, 2)
+
+
+def sort_prices(prices: list, discount):
+    prices.sort()
+    for i in range(len(prices) // 3):
+        price = prices.pop(-1)
+        price -= (price * discount)
+        prices.insert((i * 3 + 2), round(price, 2))
+    return prices
+
+
+def insert_in(prices, discount_num):
+    file = open("discount.in", 'w')
+    for elem in prices:
+        file.write(str(elem) + " ")
+    file.write("\n" + str(discount_num))
+    file.close()
+
+
+def insert_out(result):
+    file = open("discount.out", 'w')
+    file.write(str(result))
+    file.close()
+
+
+def open_file(url):
+    price_data = []
+    with open(url) as file:
+        for line in file:
+            price_data.extend([float(item) for item in line.split()])
+    return price_data
+
+
+if __name__ == '__main__':
+    insert_in([1, 2, 3, 4, 5, 6, 7], 100)
+    print(count_discount())
+    insert_out(count_discount())
diff --git a/test.py b/test.py
new file mode 100644
index 0000000..1d47129
--- /dev/null
+++ b/test.py
@@ -0,0 +1,20 @@
+import unittest
+from main import insert_in, count_discount
+
+
+class TestDiscount(unittest.TestCase):
+    def test_1(self):
+        insert_in([1, 2, 3, 4, 5, 6, 7], 100)
+        self.assertEqual(count_discount(), 15.00)
+
+    def test_2(self):
+        insert_in([65, 45, 34, 45, 53, 61, 37.5, 87.6], 45)
+        self.assertEqual(count_discount(), 359.43)
+
+    def test_3(self):
+        insert_in([1, 1, 1], 33)
+        self.assertEqual(count_discount(), 2.67)
+
+
+if __name__ == '__main__':
+    unittest.main()