import sys

N = int(input())
A = list(map(int, input().split()))
if len(A) > 1:
    print('"assert"')
    sys.exit()

A += [int(input()) for i in range(N-1)]
ans = set()

for i in range(3):
    for j in range(i+1, 3):
        ans.add(A[i]+A[j])
ans = list(ans)
ans.sort(reverse=True)
print(ans[1])