N = int(input())
a0 = input()
if a0.count(" ") :
    print('"assert"')
else :
    a0 = int(a0)
    a1 = int(input())
    a2 = int(input())
    
    A = [a0,a1,a2]

    B = {}
    for i in range(2) :
        for j in range(i+1,3) :
            key = A[i] + A[j]
            B[key] = 1
    K = list(B.keys())
    K.sort()
    print(K[-2])