diy2.py

i=3
username = "cjy3.14159265358979"
userpassword = "kimi20100702"
while True:
    if i>0:
        name = input("请输入用户名:")
        password = input("请输入密码:")
        i-=1
        if name == username and password == userpassword:
            print("登录成功!")
            break
        if name != username:
            print("用户名不存在，请重新输入！")
            continue  
        if password !=  userpassword:
            print("密码输入有误，请重新输入！") 
    else: 
        print("系统出错！！@#￥%……&*（）——+@#￥@%&#￥&")
        exit()   
print("欢迎来到贝尔编程!")