import sys
sys.setrecursionlimit(10**9)
input = sys.stdin.readline

N = int(input())
try:
    A = [int(input()) for _ in range(N)]
    cand = set()
    for i in range(N):
        for j in range(i+1, N):
            cand.add(A[i]+A[j])

    cand = list(sorted(cand))
    print(cand[-2])

except:
    print("\"assert\"")