#!/bin/python3

import sys

def pairsums(arr):
    final_sum = 0
    for i in range(len(arr)-1):
        for j in range(i+1,len(arr)):
            final_sum += arr[i]*arr[j]
    return final_sum

def drop_one(arr,length):
    right_impact = arr[length-1]*sum(arr[:length-1])
    left_impact = arr[0]*sum(arr[1:])
    if right_impact < 0 and right_impact < left_impact:
        arr = arr[:-1]
    elif left_impact < 0 and left_impact < right_impact:
        arr = arr[1:]
    return arr

def largestValue(arr):
    length = len(arr)
    final_arr = arr
    if length == 2:
        return pairsums(final_arr)
    
    new_arr = drop_one(final_arr,length)
    #print("current final_arr is", final_arr)
    #print("new_arr is", new_arr)
    while new_arr != final_arr:
        final_arr = new_arr
        length = len(final_arr)
        new_arr = drop_one(final_arr,length)
    
    return pairsums(final_arr)

if __name__ == "__main__":
    n = int(input().strip())
    arr = list(map(int, input().strip().split(' ')))
    result = largestValue(arr)
    print(result)