#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <fstream>
#include <sstream>
#include <set>
#include <map>
#include <vector>
#include <list>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <string>
#include <queue>
#include <bitset>		//UWAGA - w czasie kompilacji musi byc znany rozmiar wektora - nie mozna go zmienic
#include <cassert>
#include <iomanip>		//do setprecision
#include <ctime>
#include <complex>
using namespace std;

#define FOR(i,b,e) for(int i=(b);i<(e);++i)
#define FORQ(i,b,e) for(int i=(b);i<=(e);++i)
#define FORD(i,b,e) for(int i=(b)-1;i>=(e);--i)
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define ALL(u) (u).begin(),(u).end()

#define ST first
#define ND second
#define PB push_back
#define MP make_pair
#define LL long long
#define ULL unsigned LL
#define LD long double

typedef pair<int, int> PII;

const double pi = 3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342;


int main()
{
	int k;
	scanf("%d", &k);
	LL last = 1;
	LL sum = 1;

	FORQ(i, 2, k)
	{
		last = last + i * 2;
		sum += (i - 1)*(LL)(i - 1) * 2 + last;
	}

	printf("%lld\n", sum);

	return 0;
}