10101010 SUSTech Online Judge
Problem 1010 --N!

1010: N!

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 120  Solved: 45
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Description

Give you a integer: N. Please calculate N!.

N!= N*(N-1)...2*1

Input

An integer: N(0<N<=20)

Output

An integer: T

Sample Input

2

Sample Output

2

HINT

Source

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