using System;

public class Program

{

    public static void Main()

    {

        int choice1 = 1;

        while(choice1 >= 1)   //iteration, loop

        {

        Console.WriteLine("Choose what unit you wish to convert: 1 - Cm to Inches, 2 - Inches to CM, 3 - QUIT: ");

        int choice = Convert.ToInt16(Console.ReadLine());

            double cm = 0;

            double inches = 0;

        while(choice == 1 ^ choice == 2 ^ choice == 3)

        {

            if(choice == 1)        //branching, selection

            {

                 Console.WriteLine("Input a number in cm");

                 double cm1= Convert.ToDouble(Console.ReadLine());

                 inches = cm1* 0.393700787;

                 Console.WriteLine(inches);

                 choice1 = choice - 2;

                 break;

            }

            if(choice == 2)

            {

                 Console.WriteLine("Input a number in cm");         // sequence

                 double inch1 = Convert.ToDouble(Console.ReadLine());

                 cm = inch1 * 2.54;

                 Console.WriteLine(cm);

                 choice1 = choice - 2;

                 break;

            }

            if(choice == 3)

            {

                 Console.WriteLine("Bye");

                 choice1 = choice - 2;

                 break;

​

            }

            else

            {

                Console.WriteLine("Invalid");

            }

        }

        }

    }

}