using System;

public class Program

{

    public static void Main()

    {

        int n;

            Console.WriteLine("Nhap n: ");

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

            int i= 10;

        int s=0;

            while (n>0)

            {

                s=s+n%i;

                    n=n/10;

            }   

        Console.WriteLine("ket qua la:" + s);

    }

​

}