Which proton is more acidic in this compound?

I'm having trouble determining which of these protons is more acidic. I was thinking the solution had something to do with the double bond in the aromatic ring, but I'm still not sure. 
![enter image description here](https://i.stack.imgur.com/fcNZQ.jpg)




You could start by drawing the resonance structure of the naphthalene ring, this gives a compound in which the conditions on the two nitrogen atoms are interchanged, thus both nitrogen atoms are equivalent. As $\ce{N-H}$ bonded protons are more acidic than $\ce{C=C-H}$ protons and $\ce{N-C-H}$ protons, the answer must be the hydrogen atom bonded to the nitrogen atom, as both nitrogen atoms are equivalent, either of the hydrogen atoms is a valid answer (as they are equivalent).


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