Problem:
Sum of Numbers

Write a program which reads an integer and prints sum of its digits.

Input

The input consists of multiple datasets. For each dataset, an integer x is given in a line. The number of digits in x does not exceed 1000.

The input ends with a line including single zero. Your program should not process for this terminal symbol.

Output

For each dataset, print the sum of digits in x.

Sample Input

123
55
1000
0

Sample Output

6
10
1

Solution in C# (judge verdict: Runtime Error)

using System;

namespace ITP1
{
    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                string x = Console.ReadLine();
                if (x == "0") break;
                int sum = 0;
                int num = int.Parse(x);
                for (int i = 0; i < x.Length; i++)
                {
                    sum += num % 10;
                    num /= 10; 
                }
                Console.WriteLine(sum);
            }
        }
    }
}