using System;

public class Program

{

    static private double missingl(double a, double c) 

    { 

        double c2= c*c;

        double a2 = a*a;

        return Math.Sqrt(a2-c2);

    }

    static private double pyth(double a, double b)

    { 

        double a2 = a*a;

        double b2 = b*b;

        return Math.Sqrt(a2 + b2);

    }

    public static void Main()

    {

        string choice = "j";

        while(choice != "n" && choice != "N")

        {

            {

                Console.WriteLine("Enter 'ML' if you would like to find a missing leg or 'HYP' to find a hypatanus leg. Type in all CAPS"); 

                string input =  Console.ReadLine(); 

                if(input == "HYP")

                    {       

                        Console.WriteLine("Please enter your first value");

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

                        Console.WriteLine("Please enter your second value");

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

                        double output = pyth(input1, input2);

                        Console.WriteLine("The hypotenus of a tringle with legs " + input1 + " and " + input2 + " is " + output + "."); 

                        Console.WriteLine("Would you like to restart? y/n");

                        choice = Console.ReadLine();

                        Console.Clear();     

                    }

                 else if(input == "ML")

                    { 

                        Console.WriteLine("Please enter the hypatanus");

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

                        Console.WriteLine("Please enter the leg");

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

                        double output = missingl(input1, input2);

                        Console.WriteLine("The missing leg of a tringle a hypotenus of " + input1 + " and leg of " + input2 + " is "+  output +"."); 

                        Console.WriteLine("Would you like to restart? y/n");

                        choice = Console.ReadLine();

                        Console.Clear();

                    }    

                }

            }

        }

    }

​