using System;

public class Program

{

    static private double leg(double a, double c)

    {

        double a2 = a*a;

        double c2 = c*c;

        return Math.Sqrt(a2-c2);

    }

    static private double hyp(double a, double b)

    {

        double a2 = a*a;

        double b2 = b*b;

        return Math.Sqrt(a2+b2);

    }

    public static void Main()

    {

            start:

        Console.WriteLine(" Press 1 to caculate the leg or press 2 to caculate the hypotenuse ");

        double input = double.Parse(Console.ReadLine());

        if(input<=2)

        {

            double input1 = double.Parse(Console.ReadLine());

            double input2 = double.Parse(Console.ReadLine());

            double output = (hyp(input1, input2));

            Console.WriteLine(output);

            goto start;

        }

         else if(input<=1)

         {

            double input3 = double.Parse(Console.ReadLine());

            double input4 = double.Parse(Console.ReadLine());

            double output = (leg(input3, input4));

            Console.WriteLine(output);

            goto start;

        } 

    }

}