rot5

def (c):
  c = str(c)
  l = len(c)
  if len(c) == 1:
    c = int(c)
    if c >= 5:
      c -= 5
    else:
      c += 5
    return str(c)
  else:
    return "".join(map(rot5,[c[index] for index in range(l)]))