import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import itertools

N = int(readline())
data = readlines()

if len(data) < 3:
    print('"assert"')
    exit()

nums = list(map(int,data))

se = set(a+b for a,b in itertools.combinations(nums, 2))
answer = sorted(se, reverse=True)[1]

print(answer)