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Easymathrecursion

Factorial

Time limit 2 s · Memory 64 MB

Statement

You are given an integer n. Print n! = 1 · 2 · … · n. By definition 0! = 1.

Constraints

0 ≤ n ≤ 20

Examples

Input 1
5
Output 1
120
Input 2
0
Output 2
1
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