class Terminal:
    def __init__(self):
        self.user = None
        self.users = {}
        self.run = False

    def check_login(self):
        if self.user in self.users.keys():
            return True
        else:
            return self.do_login()

    def do_login(self):
        username = raw_input('Username: ')
        password = raw_input('Password: ')
        if username in self.users.keys():
            if password == self.users[username]:
                print 'login ok!'
                print 'Welcome %s!' % (username)
                self.user = username
                return True
        print 'login failed!'
        return False

    def commandline(self):
        cmd = raw_input('INPUT# ')
        if cmd == 'logout':
            print 'Bye!'
            self.user = None
        if cmd == 'quit':
            self.run = False

    def main(self):
        self.run = True
        while self.run:
            if self.check_login(): self.commandline()

term = Terminal()
term.users = { 'ndakota':'transltr', 'elite':'awesum' }
term.main()