n = int(input())
a = [int(i) for i in input().split()]

keta = [0]*n

for i in range(n):
    tmp = format(a[i], '0'+str(61)+'b')
    keta[i] = tmp
for i in range(61):
    for j in range(n):
        #print(j)
        if keta[j][60-i] == "1":
            break
        if j == n-1:
            #print(i)
            print(2**i)
            exit()