AccountNumber1 = []

password1 = []

flag = True

while flag:

    num = 0

    a = 1

    print('-----------这是个欢迎界面---------------')

    print('''

    1、注册账号

    2、登陆账号

    3、更改密码

    ''')

    num=input()

    if num==1:

        while a<2:

            AccountNumber=input('请您注册账号')

            if AccountNumber1.count(AccountNumber)==0:

                AccountNumber1.append(AccountNumber)

                print('您的账号是{}'.format(AccountNumber))

            else:

                print('{}这个账号已经被注册过咯！请进行其他操作！'.format(AccountNumber))

                break

            password=input('请注册您的密码')

            if password1.count(password)==0:

                # print(password1.count(password1))

                password1.append(password)

                print('您的密码是{}'.format(password))

                a+=1

    if num==2:

        x=-1

        EnterAccount=input('请输入您的账号')

        Enterpassword=input ('请输入您的密码')

        for i in AccountNumber1:

            x+=1

            if i==EnterAccount:

                if password1[x]==Enterpassword:

                    print('登陆成功！')

                    flag = False

                    break

                else:

                    print("密码不正确")

            else:

                print('账号不存在')

        else:

            print('账号不存在')

    if num == 3:

        x = -1

        for i in AccountNumber1:

            x += 1

            AccountNumber = input('请输入您的账号')

            OldPassword = input('请输入您的旧密码')

            if i == AccountNumber:

                if password1[x] == OldPassword:

                    NewPassword=input('输入您的新密码')

                    password1[x]=NewPassword

                    print('修改完毕！')

                    flag = False

                    break

                else:

                    print("密码错误，请重新输入旧密码")

            else:

                print('账号不存在或错误')

        else:

            print('账号不存在')