software - In Lightroom, how do I search for photos which match only a certain keyword?

How do I get Lightroom to return photos that contain a single word I search for?

Example:

I have pictures that I have keyworded with two names, Max and Maddie. I have pictures of Max on his own (keyword Max) pictures of Maddie on her own (keyword Maddie) pictures af them both together (keywords Max, Maddie). If I search in the keyword text for Max, I am getting the pictures of him on his own (which is what I want) but also the ones of both of them together. So, how do I get just Max on his own to return?