city_list = ['广州','深圳','东莞','佛山']

for city in city_list:
 print("当前地市为：{0}".format(city))

city_dict = {'A':'广州','B':'深圳','S':'东莞','E':'佛山'}
for code in city_dict.keys():
 city = city_dict[code]
 print("{0}的车牌代号为:粤{1}".format(city,code))

sum = 0
for i in range(1,21): # range(1,21)对应区间数为：[1,21)
 sum += i
print('数值之和为%d'%sum)

n = 0
while(n  5):
 n+=1
 print("当前值{0}".format(n))

sum = 0
n = 0
while(n  20):
 n += 1
 sum += n
print('数值之和为%d'%sum)

n = 5
pwd = "123789"
while (n > 0):
 in_str = input("请输入密码：")
 n -= 1
 if len(in_str)  6:
  print("输出密码少于6位，剩余机会{0}次，请重新输入！".format(n))
 if in_str == pwd:
  print("登录成功！")
  break
 else:
  print("输出密码错误，剩余机会{0}次，请重新输入！".format(n))

if n == 0:
 print("登录失败，请稍候再试！")