n = int(input())
a = list(map(int,input().split()))
if len(a) > 1:
    print('"assert"')
else:
    b = int(input())
    c = int(input())
    a.extend([b,c])
    tot = set()
    for i in range(3):
        for j in range(i + 1,3):
            tot.add(a[i] + a[j])
    tot = sorted(list(tot))
    print(tot[-2])