import itertools
import math
import re

input()
s = input()
res = re.match("^\d*$",s)
if (not res):
    print("\"assert\"")
else:
    a = (int(s),int(input()),int(input()))
    b = itertools.combinations(a,2)
    l = []

    for x in b:
        l.append(sum(x))

    if  (len(l) == 1):
        print("\"assert\"")
    else:
        l2 = list(set(l))
        l2.sort()
        l2.reverse()
        print(l2[1])