#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long modularExponentiation(long long base, long long power) {
  long long ans = 1;
  while (power > 0) {
    if (power & 1) ans = (ans * base) % 1000000007;
    power = power >> 1;
    base = (base * base) % 1000000007;
  }
  return ans;
}
void solve() {
  int n;
  cin >> n;
  long long ans = 0;
  long long first = 2, second = 3;
  while (second <= n) {
    ans += (first * second);
    first++;
    second++;
  }
  cout << ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
