Problem Description
Given an integer N(0 ≤ N ≤ 10000), your task is to calculate N!

 

Input
One N in one line, process to the end of file.

 

Output
For each N, output N! in one line.

 

Sample Input
1
2
3
 

Sample Output
1
2
6


算法我会，可是当N很大时用一般的数据类型都不能存储N！，这时我该怎么办呢？？

恩，谢了！！我好好研究研究