query = int(input())
for i in range(query):
  n = int(input())
  s = [int(_) for _ in str(bin(n)[2:])]
#  print(s)
  s.reverse()
  now = 1
  ans = 0
  count = 0
  for j in s:
    if j == 1:
      if count == 0:
        ans += now
        count += 1
      else:
        count += 1
    else:
      if count == 1:
      	ans += now
    now *= 2
  if count == 1:
    print(-1)
  else:
    print(ans)