N = int(input())
A = list(map(int, input().split()))
b=[0]*61
for i in range(N):
    s = 2**59
    for j in reversed(range(60)):
        if A[i]>=s:
            A[i] -= s
            b[j] += 1
        s //= 2
for i in range(61):
    if b[i] == 0:
        print(2**i)
        exit()