using System;

public class Program

{

    public static void Main()

    {

        //  EJERCICIO 1 DE 1 

        Console.WriteLine("AURA GONZALEZ");

        double a =2;

        double b = 4;

        double c = 6;

        double R = (Math.Pow(a,2)-Math.Pow(c,2)-Math.Pow(b,2))/(-2*a*b);

        Console.WriteLine("R = " + R);

    }

}