#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>
int sgn(int x) {
    if (x < 0) return -1;
    if (x > 0) return  1;
    return 0;
}
int max(int x, int y) {
    return x > y ? x : y;
}
long int largestValue(int A_size, int* A) {
    // Return the largest value of any of A's nonempty subarrays.
    // The maximum value will either come from ALL negative numbers or ALL positive
    int lastSum = 0;
    int currentSum = 0;
    int i, j;
    for(i=0; i < A_size; i++) {
        for(j = i+1; j < A_size; j++) {
            if(sgn(A[i]) * sgn(A[j]) >= 0 ) {
                currentSum += A[i] * A[j];
/*printf("%d %d %d %d\n", A[i], A[j], A[i] * A[j], currentSum);*/
            } else {
                lastSum = max(currentSum,lastSum);
                currentSum = 0;
            }
        }        
    }
    return max(lastSum, currentSum);
}

int main() {
    int n; 
    scanf("%i", &n);
    int *A = malloc(sizeof(int) * n);
    for (int A_i = 0; A_i < n; A_i++) {
       scanf("%i",&A[A_i]);
    }
    long int result = largestValue(n, A);
    printf("%ld\n", result);
    return 0;
}