using System;

using System.Linq;

using System.Math;

​

​

namespace creditCardWithSimilarSettings

{

    class Program

    {

        static void Main(string[] args)

        {

            // These string variables are for user input to avoid runtime errors.

            string firstInput, secondInput, thirdInput, fourthInput;

            // theese boolean variables are for the do while loops.

            bool testNum1, testNum2, testNum3, testNum4;

            int firstNum, secondNum, thirdNum, fourthNum; 

​

            int sec1;

​

            do

            {

               firstInput = Console.ReadLine();

                Console.WriteLine("All numbers are 0 to 9, excpet the first and last digit, which must be odd");

                Console.WriteLine("Please enter your first number");

                // firstNum = int.Parse(Console.ReadKey(true).KeyChar); didn't work

​

                if ((firstInput.All(char.IsDigit) && (firstInput == "1" || firstInput == "3" || firstInput == "5" || firstInput == "7" || firstInput == "9")))

                {

                    firstNum = Convert.ToInt16(firstInput);

                    Console.WriteLine("You choose" + firstNum);

                    testNum1 = true;

                }

​

                else

                {

                    Console.WriteLine("Please choose again");

                    testNum1 = false;

                }

            } while (testNum1 == false);

​

            Console.WriteLine("Please chose your second number");

            do

            {

                secondInput = Console.ReadLine();

                if ((secondInput.All(char.IsDigit) && (secondInput == "1" || secondInput == "2" || secondInput == "3" || secondInput == "4" || secondInput == "5" || secondInput == "6" || secondInput == "7" || secondInput == "8" || secondInput == "9" || secondInput == "0")))

                {

                    secondNum = Convert.ToInt16(secondInput);

                    Console.WriteLine("You choose" + secondNum);

                    testNum2 = true;

                }

​

                else

                {

                    Console.WriteLine("Please choose again");

                    testNum2 = false;

                }

            } while (testNum2 == false);

            Console.WriteLine("Please enter your next SINGULAR number");

            do

            {

                thirdInput = Console.ReadLine();

                if ((thirdInput.All(char.IsDigit) && (thirdInput == "1" || thirdInput == "2" || thirdInput == "3" || thirdInput == "4" || thirdInput == "5" || thirdInput == "6" || thirdInput == "7" || thirdInput == "8" || thirdInput == "9" || thirdInput == "0")))

                {

                    thirdNum = Convert.ToInt16(thirdInput);

                    Console.WriteLine("You choose" + thirdNum);

                    testNum3 = true;

                }

​

                else

                {

                    Console.WriteLine("Please choose again");

                    testNum3 = false;

                }

            } while (testNum3 == false);

            Console.WriteLine("Please enter your next SINGULAR number");

            do

            {

                fourthInput = Console.ReadLine();

                if ((fourthInput.All(char.IsDigit) && (fourthInput == "1" || fourthInput == "2" || fourthInput == "3" || fourthInput == "4" || fourthInput == "5" || fourthInput == "6" || fourthInput == "7" || fourthInput == "8" || fourthInput == "9" || fourthInput == "0")))

                {

                    fourthNum = Convert.ToInt16(fourthInput);

                    Console.WriteLine("You choose" + fourthNum);

                    testNum4 = true;

                }

​

                else

                {

                    Console.WriteLine("Please choose again");

                    testNum4 = false;

                }

            } while (testNum4 == false);

            Console.WriteLine("Your first 4 numbers are " + firstNum + secondNum + thirdNum + fourthNum);

            Console.Write();

            sec1 = (firstNum + secondNum + thirdNum + fourthNum);

            Console.WriteLine(sec1);

        }

    }

}