#include <bits/stdc++.h>
using namespace std;
int n;
long long res;
pair<int, int> a[10000];
int t = 0;
int main() {
  cin >> n;
  res = 1000000000;
  for (int i = 1; i < n; i++) {
    a[t].first = i;
    a[t].second = i + 1;
    t++;
  }
  a[t].first = 1;
  a[t].second = n;
  t++;
  for (long long i = 1; i <= n; i++) {
    long long res2 = 0;
    for (int j = 0; j < t; j++) {
      if (a[j].first != i && a[j].second != i) {
        res2 += (i * a[j].first * a[j].second);
      }
    }
    res = min(res2, res);
  }
  cout << res;
  return 0;
}
