#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;

#define LL long long

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	LL k;
	cin >> k;

	LL start = k*(k-1) / 2;
	LL result = 0;
	for (int i=0;i<k;++i) {
		result += (2*(start + i) + 1);
	}
	cout << result << endl;

}