51nod1057(python2计算n！)

题目链接：www.51nod.com/onlineJudge/questionCode.html#!problemId=1057

思路：直接for循环呗～

代码：

 n = int( raw_input() );
 ans = 1;
 for i in range(2,n+1):
     ans *= i;
 print ans;