static void Main(string[] args)
{
int threads = 1;
int factorial = 1;
Console.WriteLine("What number?");
string factorialString = Console.ReadLine();
Console.WriteLine("How many threads?");
string threadsString = Console.ReadLine();
if (int.TryParse(factorialString, out factorial) && int.TryParse(threadsString, out threads) && threads > 0 && factorial >= 0)
{
Factorial f = new Factorial();
double result = f.Calc(factorial, threads);
Console.WriteLine(result);
}
Console.ReadKey();
}