diy2.py

a=0
username = "1"
userpassword = "1"
while True:
    a = input("请输入用户名:")
    b = input("请输入密码:")
    a+=1
    if a == username and b == userpassword:
        break
        print("登录成功!")
    else:    
        
        if b !=userpassword:
            print("账号错")
        if a !=username:
            print("密码错")
    if a==3:
        print("你的帐号被锁定")
        exit()
print("欢迎来到贝尔编程!")