sys
user_file=lock_file=f=(user_file,)
user_list=f.readlines()
:username = ().strip()
    lock_list=(lock_file,)
    line lock_list.readlines():
        line = line.split()
        username == line[]:
            sys.exit(%username)
    line user_list:
        line = line.split()
        username == line[]:
            limit ():
                password = ().strip()
                password == line[]:
                    (%username)sys.exit()
            :
                (%username)
                (lock_file,) f:
                    f.write(%username)
                sys.exit()
    :
        (%username)
        sys.exit()