#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  time_point<high_resolution_clock> cc_start = high_resolution_clock::now(),
                                    cc_end;
  int n;
  cin >> n;
  --n;
  cout << ((n * (n + 1) * (n + 2)) / 3) - 2 << "\n";
  cc_end = high_resolution_clock::now();
  duration<double, milli> cc_elapsed_time = cc_end - cc_start;
  cerr << "\nElapsed Time : " << cc_elapsed_time.count() << " ms\n";
}
