recursion.cs

using System;
using System.Collections.Generic;
using System.IO;
class Solution {
    static int factorial(int thenumber) {
        if(thenumber <= 1) {
            return 1;
        } else {
            return thenumber * factorial(thenumber-1);
        }
    }
    static void Main(String[] args) {
        int wheretostart = Convert.ToInt32(Console.ReadLine());
        int theresponse = factorial(wheretostart);
        Console.WriteLine(theresponse);
    }
}