using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        int temp;

           if (int.TryParse("10", out temp))

            {

                Console.WriteLine(20 * Convert.ToInt16("10"));

            }

            else { 

                Console.WriteLine("Not a valid number");

            }

    }

}