#include<iostream>
using namespace std;
int with(int a)
{
	int sum;
	sum=1;
	for (int i=1;i<=a;i++)
	{
		sum*=i;
	}
	return sum;
}
int main()
{
	int n,num;
	cin>>n;
	for (int i=1;i<=n;i++)
	{
		num+=with(i);
	}
	cout<<num;
	return 0;
}

测试都是对的，能到50，就是全WA