#!/bin/python3

import sys

if __name__ == "__main__":
    n = int(input().strip())
    A = list(map(int, input().strip().split(' ')))
    A= A[::-1]
    while A[-1] <= A[-2] and len(A)>=2:
        A=A[:-1]
    lst,slt,add = A[-1],A[-2],A[-1]
    A=A[:-2]
    A = A[::-1]
    MAX = lst
    ans = lst*slt
    add = lst+slt
    if ans>MAX:
        MAX = ans
    for i in A:
        ans += (i*add)
        if ans>MAX:
            MAX = ans
        add += i
    print(MAX)