Add multilingual language and systems learning tracks

ceb/csharp-practice-20261101/lesson-3/main.cs

@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+class Program {
+    static int Remaining(int total, int done) { return done >= total ? 0 : total - done; }
+    static void Main() {
+        if (Remaining(4,1)!=3 || Remaining(4,4)!=0 || Remaining(4,5)!=0 || Remaining(0,0)!=0)
+            throw new Exception("Test failed");
+        Console.WriteLine("Nipasar");
+    }
+}