#include <bits/stdc++.h>

using namespace std;

int largestSum(vector <int> a, int size)
{
    int max_so_far = INT_MIN, max_ending_here = 0,
       start =0, end = 0, s=0;
 
    for (int i=0; i< size; i++ )
    {
        max_ending_here += a[i];
 
        if (max_so_far < max_ending_here)
        {
            max_so_far = max_ending_here;
            start = s;
            end = i;
        }
 
        if (max_ending_here < 0)
        {
            max_ending_here = 0;
            s = i + 1;
        }
    }
    int j = start;
    int n = start;
    int sum = 0;
    while(n < (end)) {
        sum += a[n]*a[j + 1];
        ++j;
        if(j == end) {
            j = start + n;
            n++;
        }
    }

    return sum;
}


int main() {
    int n;
    cin >> n;
    vector<int> A(n);
    for(int A_i = 0; A_i < n; A_i++){
       cin >> A[A_i];
    }
    cout << largestSum(A, n);
    return 0;
}