Is it possible to get visa when I get in China? Hong Kong,Bejing or anywhere?

I have passport from Montenegro,I dont have time to apply at embassy in my country because I must be in China on 31st so is it possible to get one when I arrive in China? I heard its possible in Bejing,just when I arrive I pay like 100 $ and they give it. Or something like this in Hong Kong? Anywhere in China?Does someone have this information ?
Very urgent please!!!