using System;

public class Program

{   static void menu()

    {

            Console.WriteLine("select anyone");

            Console.WriteLine("press 1 for area of triangle");

            Console.WriteLine("press 2 for area of rectangle");

            Console.WriteLine("press 3 for exit");

            int num=Convert.ToInt32(Console.ReadLine());

              { switch(num)

                { case 1:

                    triangle();

                    break;

                    case 2:

                    rectangle();

                    break;

                    case 3:

                    Console.WriteLine("terminated");

                break;

            }

    }}

    static void triangle()

    {   Console.WriteLine("provide base and height for the triangle");

        int b=Convert.ToInt32(Console.ReadLine());

        int h=Convert.ToInt32(Console.ReadLine());

        double area=0.5*b*h;

        Console.WriteLine(area);

        menu();

    }

    static void rectangle()

    {   Console.WriteLine("provide the lenght and breadth");

        int l=Convert.ToInt32(Console.ReadLine());

        int b=Convert.ToInt32(Console.ReadLine());

        double area=l*b;

        Console.WriteLine(area);

     menu();

    }

    public static void Main()

    {   menu();

    }

}