using System;

public class Program

{

    public static void Main()

    {

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

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

        Console.WriteLine("Enter operator: ");

        char operator_ = Convert.ToChar(Console.ReadLine());

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

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

        double answer=0;

        switch (operator_)

        {

            case '+':

                answer = first + second;

                break;

            case '-':

                answer = first - second;

                break;

            case '*':

                answer = first * second;

                break;

            case '/':

                answer = first / second;

                break;

            default:

                Console.WriteLine("Error");

                break;

        }

        Console.WriteLine("answer is: " + answer);

    }

}