diff --git a/DSA.ALGO123 b/DSA.ALGO123
new file mode 100644
index 0000000..64a22fa
--- /dev/null
+++ b/DSA.ALGO123
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+X and Y be two given sequences
+Initialize a table LCS of dimension X.length * Y.length
+X.label = X
+Y.label = Y
+LCS[0][] = 0
+LCS[][0] = 0
+Start from LCS[1][1]
+Compare X[i] and Y[j]
+    If X[i] = Y[j]
+        LCS[i][j] = 1 + LCS[i-1, j-1]   
+        Point an arrow to LCS[i][j]
+    Else
+        LCS[i][j] = max(LCS[i-1][j], LCS[i][j-1])
+        Point an arrow to max(LCS[i-1][j], LCS[i][j-1])