using System;

namespace tongsochuso

{

    class tongsochuso

    {

        public static int tong(int n)

        {

            int socuoi = 0;

            int kq = 0;

            while (n != 0)

            {

                socuoi = n % 10;

                n /= 10;

                kq = kq + socuoi;

            }

            return kq;

        }

​

        static void Main(string[] args)

        {

            Console.WriteLine("nhap n: ");

            int n = int.Parse(Console.ReadLine());

​

            int kq = tong(n);

            Console.WriteLine(kq);

        }

    }

}