#!/bin/python3
from itertools import combinations
import sys

def largestValue(A):
    a,b,c,s,x=0,0,0,0,0
    su=0
    for i in range(len(A)):
        if(a+A[i]<0):
            a=0
        else:
            a+=A[i]
        if(a>s):
            if(s==0):
                b=i
            else: c=i
            x+=1
            s=a
    for i in combinations(A[b:c+1],2):
        su+=(i[0]*i[1])
        
    return su
    
if __name__ == "__main__":
    n = int(input().strip())
    A = list(map(int, input().strip().split(' ')))
    result = largestValue(A)
    print(result)