using System;

​

public class Program

{

    public static void Main()

    {

        string str = "51200000000000000000000000000000";

        int n = 0;

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

        {

            if (str.Substring(i, 1) == "0")

                n += 1;

        }

​

        Console.WriteLine("Count : " + n.ToString());

    }

}