using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        var str = "1211";

        Console.WriteLine("{0} => {1}", str, CountAndSay(str));

    }

    static string CountAndSay(string str) {

        var builder = new StringBuilder();

        var count = 1;

        var currChar = str[0];

        for (var i = 1; i < str.Length; i++) {

            if (str[i] == currChar) {

                count++;    

            }

            else {

                builder.Append(String.Format("{0}{1}", count, currChar));

                currChar = str[i];

                count = 1;

            }

        }

        builder.Append(String.Format("{0}{1}", count, currChar));

        return builder.ToString();

    }

}