using System;

public class Program

{

    public static void Main()

    {

        Console.Write("e=");

var e=double.Parse(Console.ReadLine());

        Console.Write("f=");

        var f=double.Parse(Console.ReadLine());

        var n=(e-f)*(e+f);

        Console.Write(" n= "+ n + " e stoinostta na izraza ");

    }

}