PrimeFactorsApp

using Ch04Ex02PrimeFactorsLib;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

WriteLine("Hello! Welcome to the Prime Factors Application. You can use this application to identify all the prime factors of any integer under 1,001.");
RallyPoint:
WriteLine();
Write("Please enter a whole number that you would like to factorize: ");

double userinput = 0;
try
{
    userinput = Convert.ToDouble(ReadLine());
}
catch (Exception ex)
{
    WriteLine($"{ex.GetType} says {ex.Message}");
    goto RallyPoint;
}
WriteLine();

if (userinput > 1 && userinput < 1001)
{
    PFLib thisinstance = new();
    thisinstance.primeFactors(userinput);
}
else if (userinput > 1000)
{
    WriteLine($"{userinput} is too large for this application! The maximum value is 1,000. Would you like to try again?");
    WriteLine();
    string? answer1 = Console.ReadLine();
    if (answer1 == "Yes")
    {
        goto RallyPoint;
    }
    else if (answer1 == "No")
    {
        WriteLine("Thank you for using the prime factors app! Goodbye.");
        ReadKey();
    }
    else if (answer1 != "Yes" || answer1 != "No")
    {
        WriteLine();
        WriteLine("I'm sorry, I can't understand your answer.");
        goto RallyPoint2;
    }
}
else if (userinput <= 1)
{
    Console.WriteLine($"{userinput} does not have any prime factors!");
    WriteLine();
    WriteLine("Would you like to try again?");
    WriteLine();
    string? answer2 = Console.ReadLine();
    if (answer2 == "Yes")
    {
        goto RallyPoint;
    }
    else if (answer2 == "No")
    {
        WriteLine("Thank you for using the prime factors app! Goodbye.");
        ReadKey();
    }
    else if (answer2 != "Yes" || answer2 != "No")
    {
        WriteLine();
        WriteLine("I'm sorry, I can't understand your answer.");
        goto RallyPoint2;
    }
}
WriteLine();
RallyPoint2:
WriteLine();
WriteLine("Would you like determine the factors of another number?");
WriteLine();
string? answer3 = ReadLine();
if (answer3 == "Yes")
{
    goto RallyPoint;
}
else if (answer3 == "No")
{
    WriteLine();
    WriteLine("Thank you for using the prime factors app! Goodbye.");
    return;
}
else if (answer3 != "Yes" || answer3 != "No")
{
    WriteLine();
    WriteLine("I'm sorry, I can't understand your answer.");
    goto RallyPoint2;
}