day1--一个简单的登录接口

_usrename = "Yvan"
_password = "abc123"
count=0
while count <3:
    username = input("username:")
    password = input("password:")
    if _usrename == username and _password == password:
        print("Welcome to PY",username)
        break
    elif _usrename != username and _password ==password:
        print("The username isn't exist ,try again!")
    elif _password !=password and _usrename == username:
        print("The password is error,try again!")
    elif _usrename != username and _password != password:
        print("Error!")
    count +=1
else:
    print("You have tried too many times,please try it tomorrow.")