各位能帮忙看一下吗？为啥long long 都不够用了？ ```cpp
#include
using namespace std;
int main(){
int n;
cin>>n;
unsigned long long sum=0;
unsigned long long shortsum=1;
for(int i=1;i<=n;i++){
for(int j=1;j<=i;j++){
shortsum*=j;
}
sum+=shortsum;
shortsum=1;
}
cout<<sum;
return 0;
}
