A C# calculator.

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Calculator
{
    class Program
    {
        static void Main(string[] args)
        {
        Start: // this starts from the function, so we can loop back up
            Console.WriteLine("What function would you like? +, -, x? ");
            string function = Console.ReadLine();

            bool isDone = false;

            while (isDone == false)
            {
                if (function == "+")
                {
                    Console.WriteLine("First digit: ");
                    string first = Console.ReadLine();
                    int first_convert;

                    Int32.TryParse(first, out first_convert);

                    Console.WriteLine("Second digit: ");
                    string second = Console.ReadLine();
                    int second_convert;

                    Int32.TryParse(second, out second_convert);

                    int result;
                    result = first_convert + second_convert;

                    Console.Write("Result is {0} \n", result);
                    
                    isDone = true;
                    goto Start;
                }

                if (function == "-")
                {
                    Console.WriteLine("First digit: ");
                    string first = Console.ReadLine();
                    int first_convert;

                    Int32.TryParse(first, out first_convert);

                    Console.WriteLine("Second digit: ");
                    string second = Console.ReadLine();
                    int second_convert;

                    Int32.TryParse(second, out second_convert);

                    int result;
                    result = first_convert - second_convert;

                    Console.Write("Result is {0} \n", result);

                    isDone = true;
                    goto Start;
                }

                if (function == "x")
                {
                    Console.WriteLine("First digit: ");
                    string first = Console.ReadLine();
                    int first_convert;

                    Int32.TryParse(first, out first_convert);

                    Console.WriteLine("Second digit: ");
                    string second = Console.ReadLine();
                    int second_convert;

                    Int32.TryParse(second, out second_convert);

                    int result;
                    result = first_convert * second_convert;

                    Console.Write("Result is {0} \n", result);

                    isDone = true;
                    goto Start;
                }

                if (function == "scott")
                {
                        Console.WriteLine("SCOTT IS A LEGEND!");
                        goto Start;
                }

                if (function != "+" || function != "-" || function != "x"){
                        Console.WriteLine("Invalid function given.");
                        goto Start;
                }

            } // finishes while loop
        }
    }
}