In dilantin which hydrogen of nitrogen is more acidic?

The 3-nitrogen is most acidic. The 3-nitrogen is the nitrogen in between the two carbonyl groups at the C-2 and C-4 centers. The reason for my choice is because each of the two carbonyl group can enolize to form an imine and each enol form can resonate to the other enol form. Therefore, this enol is stabilized, making the proton at N-3 more acidic than the proton at N-1 which can only form one enol by the C-2 carbonyl.