diff --git a/lib.js b/lib.js
index 60f30ab..42f76be 100644
--- a/lib.js
+++ b/lib.js
@@ -1,13 +1,96 @@
 'use strict';
 
+function getInvitedFriends(friends, filter, maxLevel) {
+    if (!(filter instanceof Filter)) {
+        throw new TypeError();
+    }
+
+    var depth = maxLevel || -1;
+    var book = createBook(friends);
+
+    var bestFriends = friends.filter(function (friend) {
+        return friend.best;
+    }).map(function (friend) {
+        return friend.name;
+    });
+    var invitedFriends = inviteFriends(bestFriends, book, filter, depth);
+
+    return invitedFriends;
+}
+
 /**
  * Итератор по друзьям
  * @constructor
  * @param {Object[]} friends
  * @param {Filter} filter
+ * @param {Number} maxLevel
  */
-function Iterator(friends, filter) {
-    console.info(friends, filter);
+function Iterator(friends, filter, maxLevel) {
+    this.invitedFriends = getInvitedFriends(friends, filter, maxLevel);
+    this.index = 0;
+    this.friends = friends;
+}
+Iterator.prototype.next = function () {
+    if (this.done()) {
+        return null;
+    }
+
+    var name = this.invitedFriends[this.index++];
+    for (var i = 0; i < this.friends.length; i++) {
+        if (this.friends[i].name === name) {
+            return this.friends[i];
+        }
+    }
+};
+
+Iterator.prototype.done = function () {
+    return this.index >= this.invitedFriends.length;
+};
+
+function createBook(friends) {
+    return friends.reduce(function (book, friend) {
+        book[friend.name] = {
+            friends: friend.friends,
+            gender: friend.gender
+        };
+
+        return book;
+    }, {});
+}
+
+function getAllFriends(people, book) {
+
+    return people.reduce(function (allFriends, friend) {
+        return allFriends.concat(book[friend].friends);
+    }, []);
+}
+
+function filterCollection(nextInvitedFriends, invited) {
+
+    return nextInvitedFriends.filter(function (friend) {
+        return invited.indexOf(friend) === -1;
+    });
+}
+
+function inviteFriends(bestFriends, book, filter, depth) {
+    var invited = filter.filter(bestFriends, book);
+    invited.sort();
+
+    var allFriends = bestFriends;
+    depth--;
+
+    while (depth !== 0) {
+        allFriends = getAllFriends(allFriends, book);
+        var nextInvitedFriends = filter.filter(allFriends, book);
+        nextInvitedFriends = filterCollection(nextInvitedFriends, invited);
+        if (nextInvitedFriends.length === 0) {
+            break;
+        }
+        invited = invited.concat(nextInvitedFriends);
+        depth--;
+    }
+
+    return invited;
 }
 
 /**
@@ -19,7 +102,7 @@ function Iterator(friends, filter) {
  * @param {Number} maxLevel – максимальный круг друзей
  */
 function LimitedIterator(friends, filter, maxLevel) {
-    console.info(friends, filter, maxLevel);
+    Iterator.call(this, friends, filter, maxLevel);
 }
 
 /**
@@ -27,7 +110,11 @@ function LimitedIterator(friends, filter, maxLevel) {
  * @constructor
  */
 function Filter() {
-    console.info('Filter');
+    this.filter = function (invited) {
+        invited.sort();
+
+        return invited;
+    };
 }
 
 /**
@@ -36,7 +123,14 @@ function Filter() {
  * @constructor
  */
 function MaleFilter() {
-    console.info('MaleFilter');
+    this.filter = function (invited, book) {
+        var inv = invited.filter(function (friend) {
+            return book[friend].gender === 'male';
+        });
+        inv.sort();
+
+        return inv;
+    };
 }
 
 /**
@@ -45,9 +139,20 @@ function MaleFilter() {
  * @constructor
  */
 function FemaleFilter() {
-    console.info('FemaleFilter');
+    this.filter = function (invited, book) {
+        var inv = invited.filter(function (friend) {
+            return book[friend].gender === 'female';
+        });
+        inv.sort();
+
+        return inv;
+    };
 }
 
+FemaleFilter.prototype = Object.create(Filter.prototype);
+MaleFilter.prototype = Object.create(Filter.prototype);
+LimitedIterator.prototype = Object.create(Iterator.prototype);
+
 exports.Iterator = Iterator;
 exports.LimitedIterator = LimitedIterator;