Problem B: 求n!

Problem B: 求n!

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 2  Solved: 2
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Description

n! = 1 * 2 * …… * n 
用递归的方法求n!


Input

n (n<=50)

Output

n!

Sample Input Copy 

4

Sample Output Copy 

24

HINT

递归
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