url传值错误

ValueError at /add/

invalid literal for int() with base 10: '‘6’'

Request Method:	GET
Request URL:	http://127.0.0.1:8000/add/?a=6&b=%E2%80%986%E2%80%99
Django Version:	1.11
Exception Type:	ValueError
Exception Value:	invalid literal for int() with base 10: '‘6’'
Exception Location:	D:hackPython我的学习Djangoweb1calcviews.py in add, line 6
Python Executable:	C:Usersjumz-GAppDataLocalProgramsPythonPython35-32python.exe
Python Version:	3.5.0
Python Path:	['D:\hack\Python\我的学习\Django\web1', 'C:\Users\jumz-G\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django-1.11-py3.5.egg', 'C:\Users\jumz-G\AppData\Local\Programs\Python\Python35-32\lib\site-packages\pytz-2016.10-py3.5.egg', 'C:\Users\jumz-G\AppData\Local\Programs\Python\Python35-32\python35.zip', 'C:\Users\jumz-G\AppData\Local\Programs\Python\Python35-32\DLLs', 'C:\Users\jumz-G\AppData\Local\Programs\Python\Python35-32\lib', 'C:\Users\jumz-G\AppData\Local\Programs\Python\Python35-32', 'C:\Users\jumz-G\AppData\Local\Programs\Python\Python35-32\lib\site-packages']
Server time:	Sat, 24 Dec 2016 11:08:55 +0000

他是这么报错的

我们穿的值是6和‘6’！

但是在我们的代码里面 都会把它int（）

c=str(int(a)*int(b))