croocked digit

using System;

namespace Telerik
{
    public class Program
    {
        static void Main(string[] args)
        {
            var input = Console.ReadLine().ToCharArray() ;

            while (input.Length > 1)
            {
                int result = 0;
                for (int i = 0; i < input.Length; i++)
                {
                    if (char.IsDigit(input[i]))
                    {
                        result += input[i] - 48;
                    }
                }
                input = result.ToString().ToCharArray();
            }
            Console.WriteLine(input) ;
        }
    }
}