using System;

using System.Collections.Generic;

​

using System.Text;

​

public class Program

{

    public static void Main()

    {

            string input = "A2B2C2D2A5B7CEFZ2";

            char[] inputChars = input.ToCharArray();

            string tmpInput = "23456789";

            StringBuilder outputSB = new StringBuilder();

            for (int i = 0; i < inputChars.Length; i++)

            {

                if (tmpInput.Contains(inputChars[i+1].ToString()))

                {

                    for (int j = 0; j < Convert.ToInt32(inputChars[i + 1].ToString()); j++)

                    {

                        outputSB.Append(inputChars[i]);

                    }

​

                        i = i + 1;

                }

                else

                {

                    outputSB.Append(inputChars[i]);

                }

            }

​

            Console.WriteLine(outputSB.ToString());

    }

}