using System;

public class Program

{

    public static void Main()

    {

        string userInputA;  

        int a;

        string userInputB;  

        int b;

        do {

            Console.Write("Enter a Number: ");

            userInputA = Console.ReadLine();

        } while (!int.TryParse(userInputA, out a));

        do {

            Console.Write("Enter Another Number: ");

            userInputB = Console.ReadLine();

        } while (!int.TryParse(userInputB, out b));

        bool divisionAllowed = true;

        if (b == 0) {

            divisionAllowed = false;

        }

        char [] operations = {'+', '-', '*', '/'};

        string userInputOperation;

        char operation;

        do {

            Console.Write("Enter Operation (+, -, *, /): ");

            userInputOperation = Console.ReadLine();

        } while (!char.TryParse(userInputOperation, out operation) || !Array.Exists(operations, element => element == operation));

        switch (operation) {

            case '+':

                Console.WriteLine($"{a} + {b} = {a + b}");

                break;

            case '-':

                Console.WriteLine($"{a} - {b} = {a - b}");

                break;

            case '*':

                Console.WriteLine($"{a} * {b} = {a * b}");

                break;

            case '/':

                Console.Write($"{a} / {b} = ");

                if (divisionAllowed) {

                    Console.WriteLine($"{a / b}");

                } else {

                    Console.WriteLine("Error");

                }

                break;

        }

    }

}