# https://yukicoder.me/problems/no/1674
# No.1674 Introduction to XOR

N = int(input())
A = list(map(int, input().split()))

bits = 0
for a in A:
    bits |= a

B = bin(bits)
for i, b in enumerate(B[::-1]):
    if b in ("0, b"):
        print(1 << i)
        exit()