def main():
  from sys import stdin
  readline=stdin.readline
  n = int(readline())
  #s = input()
  #a,b = map(int, input().split())
  A = list(map(int, input().split()))
  for i in range(61):
    flag = True
    for a in A:
      if (a >> i) & 1 == 1:
        flag = False
    if flag:
      ans = 1 << i
      break 
  print(ans)
main()