rt

#include<bits/stdc++.h>
using namespace std;
unsigned long long fun(unsigned long long n)
{
	unsigned long long s=1;
	for(int i=1;i<=n;++i)
	{
		s*=i;
	}
	return s;
}
int main()
{
	unsigned long long  n,f=0;
	cin>>n;
	for(unsigned long long i=1;i<=n;++i)
	{
		f=+fun(i);
	}
	cout<<f;
	return 0;
}