def genBigBigNum():
  switch = random.randint(1, 10)
  if switch % 2 == 0:
    return gd.genBigBigNum()
  else:
    return -gd.genBigBigNum()
def genQRPair():
  """ Return y, x such that 0 < x <= y < BIN_LIMIT * x """
  x = gd.genBigBigNum()
  y = random.randint(x, x * BIN_LIMIT - 1)
  return y, x