while True:
  km = float(input('请输入公里数：'))
  if km <= 0:
    print('公里数输入错误，重新输入：')
    break
  else:
    if km <= 2 and km > 0:
      print('您需要支付8元车费！')
    if km >2 and km <= 12:
      cost = 8 + (km - 2) * 1.2
      print('您需要支付 %s'%cost,'元车费！')
    if km > 12:
      cost = 8 +(12 - 2) * 1.2 + (km -12)*1.5
      print('您需要支付%s'%cost,'元车费!')

while True:
  km=int(input('请输入公里数：'))
  while km <0:
    print('输入有误，重新输入：')
    break
  if km>0 and km<=2:
    print('花费8元')
  elif km>2 and km <=12:
    cost=8+(km-2)*1.2
    print('花费%s元'%cost)
  elif km>12:
    cost=8+(12-2)*1.2+(km-12)*1.5
    print('花费%s元'%cost)