#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;


int main() {

    int n;

    cin >> n;

    vector <int> a(n);

    for (int i = 0; i < n; i++) cin >> a[i];

    vector <vector<int>> dp(n, vector<int>(n, 0));

    for (int len = 2; len <= n; len++) {
        for (int left = 0; left + len - 1 < n; left++) {
            int right = left + len - 1;
            if (len == 2)
                dp[left][right] = 0;
            else {
                dp[left][right] = 1000 * 1000 * 1000;
                for (int mid = left + 1; mid <= right - 1; mid++)
                    dp[left][right] = min(dp[left][right], (a[left] + a[right]) * a[mid] + dp[left][mid] + dp[mid][right]);
            }
        }
    }

    cout << dp[0][n - 1];

    return 0;
}