using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(compressRLE("TEST"));

        Console.WriteLine(compressRLE("AABBBCCCCDDDDD"));

        Console.WriteLine(compressRLE("AABBC"));

        Console.WriteLine(compressRLE("DISNOWORK"));

​

    }

    public static String compressRLE(string input) {

        string output = "";

        int counter = 0;

        for (int i = 0; i < input.Length - 1; i++) {

            counter = 1;

            while (i < input.Length - 1 && input[i] == input[i + 1]) {

                counter++;

                i++;

            }

            output += counter.ToString() + input[i];

        }

        return output;

    }

}