#!/bin/python

import sys


n = int(raw_input().strip())
a = map(int, raw_input().strip().split(' '))
# your code goes here

def absolute_difference(n, a):
    arr = []
    for i in range(len(a)):
        for j in range(len(a) - 1):
            arr.append(a[i] + a[j + 1])
    min_diff = None
    for item in arr:
        if item > min_diff:
            if min_diff == None or item > min_diff:
                min_diff = item
    return min_diff

print(absolute_difference(n, a))