n = int(input())
l = list(map(int,input().split()))
if len(l) == 3:
    print("\"assert\"")
else:
    a = l[0]
    b = int(input())
    c = int(input())
    L = sorted(list(set([a+b,b+c,c+a])))
    if len(L) == 3:
        print(L[1])
    else:
        print(L[0])