python登入系统

print('----------欢迎您使用本系统------------')
storage_name = []  # 用列表储存用户名
storage_user = {'yuan': 'yuan111'}  # 用字典将用户名设为建 密码为值
s = ['傻', '蠢', '笨', '呆', '愚']
choice = input('您是否注册过账号 没有请注册 1：注册 2：登录 3：退出系统\n')
yi = True
if choice == '1':
    print("----------注册账号----------")
    while yi:
        pan = True
        while pan:
            user_name = input('请输入用户名：')
            username_list = list(user_name)
            for i in username_list:
                if i in s:
                    print("用户名不合法请重新输入：")
                    pan = True
                    break
                else:
                    pan = False
        pan = True
        password = input("输入密码不少于6位，需要有数字和字母：")
        while pan:
            a = len(password)
            if a < 6:
                password = input("请重新输入密码不少于6位，需要有数字和字母：")
            else:
                if password.isdigit() or password.isalpha():
                    password = input("密码不能为纯数字或纯字母，请重新输入：")
                else:
                    pan = False
                    storage_name.append(user_name)
                    for item in storage_name:
                        if item not in storage_user:
                            storage_user[item] = password
                            yi = False
                            choice = '2'
                        else:
                            print("用户名重复")
                            print("注册失败")
                            storage_name.clear()
                            break
if choice == '2':
    print("----------登入账号----------")
    n1 = 0   # 记录密码错误次数
    n2 = 0   # 记录账号错误次数
    name = input('请输入用户名:')
    pan = True
    while pan:
        if name in storage_user:
            key = input('请输入密码:')
            while pan:
                if storage_user[name] == key:
                    print('登录成功')
                    pan = False
                    break
                else:
                    n1 += 1
                    if n1 >= 3:
                        print("错误次数过多，禁止登入此系统")
                        pan = False
                        break
                    print("密码错误，还有%d次机会" % (3-n1))
                    key = input("请重新输入：")
        else:
            n2 += 1
            if n2 >= 3:
                print("错误次数过多，禁止登入此系统")
                pan = False
                break
            print("用户名错误，还有%d次机会" % (3 - n2))
            name = input("请重新输入：")