在讨论《50求调》回复：

@[wusheng_](luogu://user/1795848)@[_Kasty_](luogu://user/1653524) 谢谢

```cpp #include using namespace std; unsigned long long n,s,a=1; int main(){ cin >> n; for(int i = 1;i<=n;i++){ a*=i; s=s+a; } cout<<s; return 0; } ``` 如过必关