username = [] password = [] f1 = open("username_list.txt") for  name in f1.readline():       username.append(name.strip('\n')) f1.close() f2 = open('password_list.txt') for  pwd in f2.readline():     for pwd in  f2.readline():         f2.close()         name = input("please input username:")         times = 0 while name in username:     f3 = open('lock_list.txt')     lock = []     for line in f3.readline():         lock.append(line.strip('\n'))     f3.close()     if name in lock:         print("you count is locking")         break     pwd = input("please input you password:")     if pwd in password:         print("welcome you login the system!")         break     else:         print("your password is wrong")         times += 1         if times ==3:             print("your account is locked")             f = open('lock_list.txt','a')             f.write('%s\n'%name)             break         else:             print("your username is wrong")