def nasu(s):
  k = s ** (1 / 2)
  return int(k)

def main():
  N = int(input())
  b = bin(N)[2:]
  c = b[:len(b) // 2]
  k = -(-len(b) // 2)
  if c == "": c = "0"
  mi = int(c, 2) << k
  ma = (int(c, 2) + 1) << k

  s = mi
  while s < ma:
    t = nasu(s)
    nx = (t + 1) ** 2
    m = N ^ t 
    if s <= m < nx:
      print(m)
      break
    s = nx
  else:
    print(-1)

T = int(input())
for _ in range(T):
  main()