n = int(input())
A = list(map(int, input().split()))
B = [0]*70
for a in A:
    b = format(a, 'b')
    b = list(b)
    b.reverse()
    for i in range(len(b)):
        if b[i] == '1':
            B[i] = 1
for i in range(70):
    if B[i] == 0:
        print(1<<i)
        exit()