#include <bits/stdc++.h>
using namespace std;
const long long int N = 1e3 + 10;
const long long int INF = 2e9;
long long int n, m, cnt;
void solve() {
  cin >> n;
  long long int wyn1 = 0, sum1 = 0;
  long long int nax1 = 1, nax2 = 2, nax3 = 3;
  while (wyn1 != n) {
    sum1 += (nax1 * nax2 * nax3);
    long long int yo = nax3;
    wyn1 = nax3;
    nax2 = nax3;
    nax3++;
  }
  cout << sum1;
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long int t = 1;
  while (t--) solve();
  return 0;
}
