using System;

public class Program

{

    public static void Main()

    {           

        var a = 0;

        var b = 0;

        var shouldRun = true;

        while(shouldRun)

        {

            Console.Clear();

            Console.WriteLine("Calculate the sum of 2 numbers");

            Console.WriteLine("a = ");

            var inputA = Console.ReadLine();

            var isInputAParsed = int.TryParse(inputA, out a);

            Console.WriteLine("b = ");

            var inputB = Console.ReadLine();

            var isInputBParsed = int.TryParse(inputB, out b);

            if( isInputAParsed && isInputBParsed)

            {

                var sum = a + b;

                Console.WriteLine(a + " + " + b + " = " + sum );

                Console.WriteLine("Do you want to try again? Press Y and ENTER for running againe, any key and enter for exit");

                var result = Console.ReadLine();

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

                {

                    shouldRun = true;

                }

                else

                {

                    shouldRun = false;

                }

            }

            else

            {

                Console.WriteLine("Please enter a number!!");

                Console.WriteLine("Press any key to try again....");

                Console.ReadLine();

                shouldRun = true;

            }

        }

    }

}