#include<bits/stdc++.h>

using namespace std;

#define lowbit(x) ((x)&(-x))

typedef long long LL;

typedef pair<int,int> pii;

const LL INF = 0x3f3f3f3f3f3f3f3f;

const int maxn = ;

LL dp[maxn][maxn];

void run_case() {

    int n; cin >> n;

    for(int i = n-; i >= ; --i) {

        for(int j = i+; j <= n; ++j) {

            dp[i][j] = INF;

            for(int k = i+; k < j; ++k)

                dp[i][j] = min(dp[i][j], dp[i][k]+dp[k][j]+i*j*k);

        }

    }

    cout << dp[][n];

}

int main() {

    ios::sync_with_stdio(false), cin.tie();

    cout.flags(ios::fixed);cout.precision();

    //int t; cin >> t;

    //while(t--)

    run_case();

    cout.flush();

    return ;

}