Problem G: n!的和

Problem G: n!的和

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 4  Solved: 3
[Status] [Submit] [Creator:]

Description

求1!+2!+3!+...+n!的和

Input

输入n
n<=20

Output

一个大整数，表示阶乘的和

Sample Input Copy 

5

Sample Output Copy 

153
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