using System;

public class Pentagono

{

    public int perimetro;

    public int apotema;

    public void Area()

    {

        Console.WriteLine(perimetro*apotema/2);

    }

}

public class Programa

{

    public void Main()

    {

    Pentagono pentagono = new Pentagono();

        Console.WriteLine("perimetro");

        pentagono.perimetro = Convert.ToInt32(Console.ReadLine());

        Console.WriteLine("apotema");

        pentagono.apotema = Convert.ToInt32(Console.ReadLine());

        pentagono.Area();

    }

}