using System;

public class Program

{ static decimal pi = 3.14159M;

     static private decimal cone(decimal r, decimal h)

 {return r*r*pi*h/3;}

 static private decimal cone2(decimal r, decimal h)

 {return pi*r*h + pi*r*r;}

 static private decimal cylinder(decimal r, decimal h)

 {return r*r*pi*h;}

 static private decimal cylinder2(decimal r, decimal h)

 {return pi*2*r*r + pi*r*h*2;}

     static private decimal sphere(decimal r)

 {return pi*4/3*r*r*r;}

 static private decimal area(decimal r)

 {return pi*4*r*r;}

    public static void Main()

    {

        {start:

        Console.WriteLine("Hello, please choose an option from the menu");

        Console.WriteLine("If you would like to calculate the density of a cone, please press 1.");

        Console.WriteLine("If you would like to calculate the volume and surface area of a cylinder , please press 2.");

        Console.WriteLine ("If you would like to calculate the volume and surface area of a sphere, please press 3.");

     string choice = Console.ReadLine();

        if(choice == "1")

        {Console.WriteLine("Please Enter the radius of your cone.");

         decimal radius = decimal.Parse(Console.ReadLine());

         Console.WriteLine("Please Enter the height of your cone.");

         decimal height = decimal.Parse(Console.ReadLine());

         Console.Clear();

         Console.WriteLine("The volume of your cone is: " + cone(radius, height).ToString("##.##")); 

        Console.WriteLine("The surface area of your cone is: " + cone2(radius, height).ToString("##.##")); 

        }

        else if(choice == "2")

        {Console.WriteLine("Please Enter the radius of your cylinder.");

         decimal radius = decimal.Parse(Console.ReadLine());

         Console.WriteLine("Please Enter the height of your cylinder.");

         decimal height = decimal.Parse(Console.ReadLine());

         Console.Clear();

         Console.WriteLine("The volume of your cylinder is: " + cylinder(radius, height).ToString("##.##")); 

         Console.WriteLine("The surface area of your cylinder is: " + cylinder2(radius, height).ToString("##.##")); 

        }

        else if(choice == "3")

        {Console.WriteLine("Please Enter the radius of your sphere.");

         decimal radius = decimal.Parse(Console.ReadLine());

         Console.Clear();

         Console.WriteLine("The volume of your sphere is: " + sphere(radius).ToString("##.##")); 

         Console.WriteLine("The surface area of your sphere is: " + area(radius).ToString("##.##")); 

        }

         {

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

string decision = Console.ReadLine(); 

if (decision == "Y" || decision == "y")

{

Console.Clear(); 

goto start; 

}

         }

        }

    }

    }

​