# -*- coding: utf-8 -*-raw_input('username: ')n = raw_input('passward: ')x = 0if n == '123':    print '登录成功'else:    print '登录失败'while n != '123' and x < 3:    n = raw_input('try again: ')    x = x + 1    if x == 3:    print '失败'else:    pass

登录程序（可重试三次）