using System;

public class CalculateFactorial

{

    public static void Main()

    {

        Console.WriteLine("Please enter a number to calculate the factorial for:");

        String nString = Console.ReadLine();

        int n=0;

        int.TryParse(nString, out n);

        CalculateFactorial program = new CalculateFactorial();

        int factorial = program.calculateFactorial(n);

        Console.WriteLine("Factorial of "+n + " is " + factorial);

    }

    private int calculateFactorial(int n){

        int fact = 1;

        while(n>1){

            fact = fact * n;

            n = n-1;

        }

        return fact;

    }

}