using System;

​

public class Program

{

    public static void Main()

    {

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

        int c = 0;

        c = 1;

        c = 2;

        c = 3;

        c = 4;

        c = 5;

        c = 6;

        c = 7;

        c = 8;

        c = 9;

        c = 10;

        c = 11;

        c = 12;

        c = 13;

        c = 14;

        c = 15;

        c = 16;

        c = 17;

        c = 18;

        c = 19;

        c = 20;

        c = c + i;

        Console.WriteLine(c);

​

    }

}