#include <bits/stdc++.h>

using namespace std;

int start, end1;

void maxSubArraySum(vector <int> a, int size)
{
    int max_so_far = INT_MIN, max_ending_here = 0;
    start = 0;
    end1 = 0;
    for (int i = 0; i < size; i++)
    {
        
        max_ending_here = max_ending_here + a[i];
        if (max_so_far < max_ending_here)
        {
            max_so_far = max_ending_here;
            end1 = i;
        }
 
        if (max_ending_here < 0)
        {
            max_ending_here = 0;
            start = i+1;
        }
    }
}

long largestValue(vector <int> A, int n) {
    // Return the largest value of any of A's nonempty subarrays.
    maxSubArraySum(A,n);
    int sum1=0, sum2=0;
    for(int i=start; i<=end1; i++)
    {
        sum1 = sum1 + A[i];
        sum2 = sum2 + A[i]*A[i];
    }
    return sum1*sum1-sum2;
}

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,n);
    cout << result/2 << endl;
    return 0;
}