#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,i=1,s=0,j=0;
	cin>>n;
	while(s+i<n){
		s+=i*i;
		j+=i;
		i++;
	}
	s+=(n-j)*i;
	cout<<s;
	return 0;
}

/**************************************************************
	Problem: 1520
	User: zzz
	Language: C++
	Result: Wrong Answer
****************************************************************/