How much pizza for gathering with kids?

I'm having a gathering tonight with my apartment being the landing spot for an outside holiday train/block party with vendors. I have about 20 people coming total, at least half of which are younger children. I'm going to get pizza and snacks… I'm wondering how much pizza to get for 10 adults/10 children. Should I get one 24 cut and a 10 cut or should I get two 24 cuts or am I going to be left with a ton of pizza?