#include <bits/stdc++.h>
using namespace std;
int n;
long long dp[510][510];
int opt[510][510];
long long cal(int x, int y, int z) {
  return (long long)x * (long long)y * (long long)z;
}
int main() {
  scanf("%d", &n);
  memset(dp, -1, sizeof(dp));
  memset(opt, -1, sizeof(opt));
  for (int len = 1; len <= n; ++len) {
    for (int i = 1, j = len; j <= n; ++i, ++j) {
      if (len < 3) {
        dp[i][j] = 0;
        continue;
      }
      if (len == 3) {
        dp[i][j] = cal(i, i + 1, j);
        continue;
      }
      int l = i + 1, r = j - 1;
      if (opt[i][j - 1] != -1 && opt[i][j - 1] > l) l = opt[i][j - 1];
      if (opt[i + 1][j] != -1 && opt[i + 1][j] < r) r = opt[i + 1][j];
      for (int k = l; k <= r; ++k) {
        if (dp[i][k] == -1 || dp[k][j] == -1) continue;
        long long tmp = dp[i][k] + dp[k][j] + cal(i, j, k);
        if (dp[i][j] == -1 || tmp < dp[i][j]) dp[i][j] = tmp, opt[i][j] = k;
      }
    }
  }
  printf("%d\n", dp[1][n]);
  return 0;
}
