#include <bits/stdc++.h>

using namespace std;

long largestValue(vector<int> &A, int start, int end, unordered_map<int, unordered_map<int, long>> &memo) {
    // TODO: Maybe the condition is < 1, depends if we allow non-pairs
    if (end - start < 2) return 0;
    if (memo.count(start) && memo.count(end)) return memo[start][end];
    
    long valueLeft = largestValue(A, start + 1, end, memo);
    long valueRight = largestValue(A, start, end - 1, memo);
    
    long sum = 0;
    
    for (int i = start; i < end; i++) {
        for (int j = i + 1; j <= end; j++) {
            int product = A[i] * A[j];
            sum += product;
        }
    }
    
    memo[start][end] = max(max(valueLeft, valueRight), sum);
    
    return memo[start][end];
}

long largestValue(vector<int> &A) {
    unordered_map<int, unordered_map<int, long>> memo;
    return largestValue(A, 0, A.size() - 1, memo);
}

int main() {
    int n;
    cin >> n;
    vector<int> A(n);
    for(int A_i = 0; A_i < n; A_i++){
       cin >> A[A_i];
    }
    long result = largestValue(A);
    cout << result << endl;
    return 0;
}