from yogi import *

n1 = scan(int)
while n1 is not None:
  v1 = [read(float) for i in range(0, n1)]
  n2 = read(int)
  v2 = [read(float) for i in range(0, n2)]
  res = diferencia(v1, v2)
  n3 = len(res)
  print(n3)
  for x in res: print(" {0:.4f}".format(x), end = '')
  print('\n')
  for i in range(0, 200):
    res2 = diferencia(v1, v2)
    if res2 != res: print("Resultats diferents amb la mateixa entrada!")
  n1 = scan(int)

