#include <bits/stdc++.h>
using namespace std;
int ar[500 + 5];
int main() {
  int n, sol;
  for (int i = 0; i < 500 + 5; i++) ar[i] = i;
  cin >> n;
  sol = 0;
  for (int i = 1, j = 2; j < n; j++) {
    sol += (ar[j] * ar[j + 1]);
  }
  cout << sol << endl;
  return 0;
}
