题解

#include <iostream>
using namespace std;
int func(int n) {
int sum = 0;
for (int i = 1;i <=n;i++) {
int p=1;
for (int j = 1;j <= i;j++) {
p*=j;
}
sum+=p;
}
return sum;}
int main() {
int n;
cin >> n;
cout<<func(n);
return 0;
}