#include <algorithm>
using namespace std;
typedef long long ll;
const int MAXN = 505;
const ll INF = 1e18;
ll dp[MAXN][MAXN];

int main()
{
    int n;
    cin >> n;
    // len=2，两点，代价0
    for(int i = 1; i <= n; ++i)
        dp[i][i+1] = 0;

    // len：区间点的数量，从3到n
    for(int len = 3; len <= n; ++len)
    {
        for(int i = 1; i + len - 1 <= n; ++i)
        {
            int j = i + len - 1;
            dp[i][j] = INF;
            // 枚举分割点k
            for(int k = i+1; k < j; ++k)
            {
                ll val = dp[i][k] + dp[k][j] + 1LL * i * k * j;
                dp[i][j] = min(dp[i][j], val);
            }
        }
    }
    cout << dp[1][n] << endl;
    return 0;
}