#include <bits/stdc++.h>
using namespace std;
const int maxn = 510;
const int inf = 0x3f3f3f3f;
int n;
long long d[maxn][maxn];
int w(int i, int j, int k) { return i * j * k; }
int main() {
  int n;
  scanf("%d", &n);
  memset(d, 0x3f, sizeof(d));
  for (int i = 1; i <= n; i++) {
    d[i][i + 2] = w(i, i + 1, i + 2);
    d[i][i] = 0;
    d[i][i + 1] = 0;
  }
  for (int i = n - 2; i >= 1; i--) {
    for (int j = i + 2; j <= n; j++) {
      for (int k = i + 1; k < j; k++) {
        d[i][j] = min(d[i][j], d[i][k] + d[k][j] + w(i, j, k));
      }
    }
  }
  printf("%I64d", d[1][n]);
  return 0;
}
