#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

long int largestValue(int A_size, int* A) {
    // Return the largest value of any of A's nonempty subarrays.
    
    long int sum = 0;
    long int sumSq = 0;
    for (int i=0; i<A_size; i++) {
            sum += A[i];
            sumSq += (A[i]*A[i]);
    }
    
    long int val = (sum*sum - sumSq)/2;
    //printf("Full array val %ld\n", val);
    
    // Trim the front if that improves
    int front = 0;
    long int newVal = val - (sum-A[front])*A[front];
    while (newVal >= val) {
        //printf("Removing front %d\n", A[front]);
        sum -= A[front];
        front++;
        val = newVal;
        newVal = val - (sum-A[front])*A[front];
    }
   //printf("Val after  front %ld\n", val);
    
    // Trim the back if that improves
    int back = A_size-1;
    newVal = val - (sum-A[back])*A[back];
    while (newVal >= val) {
        //printf("Removing back %d\n", A[back]);
        sum -= A[back];
        back--;
        val = newVal;
        newVal = val - (sum-A[back])*A[back];
    }
    //printf("Val after back %ld\n", val);

    return val;
}

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;
}