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

n = int(readline().strip())
a = [int(x) for x in readline().strip().split()]
if (len(a) == 3):
    print('"assert"')
    exit()

a = [a[0]]
for i in range(2):
    a.append(int(readline().strip()))

cans = []
for i in range(len(a)):
    for j in range(i + 1, len(a)):
        total = a[i] + a[j]
        if total not in cans:
            cans.append(total)

cans = sorted(cans, reverse=True)
print(cans[1] if len(cans) > 1 else cans[0])