using System;  

​

public class SimpleCalculator  

{

    public static void Main() 

    {

        while (true)  

        {

            Console.WriteLine("\nA simple calculator program:");

            Console.WriteLine("Enter 'E' to quit the program.");

​

            Console.Write("Enter first number: ");

            string input1 = Console.ReadLine();  

​

            if (input1.ToLower() == "E")

                break;  

​

            Console.Write("Enter second number: ");

            string input2 = Console.ReadLine();  

​

            if (input2.ToLower() == "E")

                break;  

​

            int num1, num2;

            if (!int.TryParse(input1, out num1) || !int.TryParse(input2, out num2))

            {

                Console.WriteLine("Invalid!!!!! enter valid numbers");

                continue;  

            }

​

            Console.WriteLine("\nChoose a math operator: ");

            Console.WriteLine("1 - Addition");

            Console.WriteLine("2 - Subtraction");

            Console.WriteLine("3 - Multiplication");

            Console.WriteLine("4 - Division");

            Console.Write("choose your choice: ");

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

​

            switch (choice)

            {

                case 1:  

                    Console.WriteLine($"The result: {num1} + {num2} is: {num1 + num2}");

                    break;

                case 2:  

                    Console.WriteLine($"The result {num1} - {num2} is: {num1 - num2}");

                    break;

                case 3:  

                    Console.WriteLine($"The result: {num1} * {num2} is: {num1 * num2}");

                    break;

                case 4:  

                    if (num2 == 0)  

                    {

                        Console.WriteLine($"Error Division by zero is not allowed");

                    }

                    else

                    {

                        Console.WriteLine($"The result: {num1} / {num2} is: {num1 / num2}");

                    }

                    break;

                default:  

                    Console.WriteLine("Invalid");

                    break;

            }

        }

​

        Console.WriteLine("Done");

    }

}

//babawi ako 2nd quarter