#include<iostream>
using namespace std;

int main(){
	int s=0;
	int n; 
	cin>>n;
	for	(int i=1;i<=n;i-3){
		s=s+i*i;
	}
	cout<<s;
	return 0;
}
/**************************************************************
	Problem: 1054
	User: linweilun
	Language: C++
	Result: Time Limit Exceed
****************************************************************/