namespace creditCardWithSimilarSettings
static void Main(string[] args)
string firstInput, secondInput, thirdInput, fourthInput;
bool testNum1, testNum2, testNum3, testNum4;
int firstNum, secondNum, thirdNum, fourthNum;
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");
if ((firstInput.All(char.IsDigit) && (firstInput == "1" || firstInput == "3" || firstInput == "5" || firstInput == "7" || firstInput == "9")))
firstNum = Convert.ToInt16(firstInput);
Console.WriteLine("You choose" + firstNum);
Console.WriteLine("Please choose again");
} while (testNum1 == false);
Console.WriteLine("Please chose your second number");
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);
Console.WriteLine("Please choose again");
} while (testNum2 == false);
Console.WriteLine("Please enter your next SINGULAR number");
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);
Console.WriteLine("Please choose again");
} while (testNum3 == false);
Console.WriteLine("Please enter your next SINGULAR number");
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);
Console.WriteLine("Please choose again");
} while (testNum4 == false);
Console.WriteLine("Your first 4 numbers are " + firstNum + secondNum + thirdNum + fourthNum);
sec1 = (firstNum + secondNum + thirdNum + fourthNum);