C语言网题目 1014: [编程入门]阶乘求和

#include<iostream>
using namespace std;

long Sum(int n)
{
	long long sum=0,fact=1;
	for (int i=1;i<=n;i++)
	{
		fact*=i;
		sum+=fact;
	}
	return sum;
}
int main()
{
	int n;
	cin >> n;
	cout << Sum(n);
	return n;
 }