using System;

public class Program

{

    public static void Main()

    {

        int fib =0;

        Console.WriteLine("Enter any number");

        fib = Convert.ToInt16(Console.ReadLine());

        if (fib <2)

        {

            Console.WriteLine(1);

        }   

        else

        {

            Console.WriteLine((fib -1)+(fib -2));

        }

    }

}