You are a silly, silly man.
Obviously you could only have keys that would allow you a complete song, and with only ten keys, it'll have to be Chopsticks or Heart and Soul let's see...
Chopsticks, you'll need from the F below middle C up to the A above it. That's exactly ten keys.
Heart and Soul, the left player will need the notes for the chords C, Am, F, G. That's F, G, A, B, C, D, E, G, taking up eight keys. Doesn't leave a helluva lot for the poor old right-hand pianist.
---
This signature has performed an illegal operation and has been shut down.