For what application you want to use this. For input-1 the two combinations of tri-state buffers (above n below one) stores 1 and for input-0, they store 0, i suppose.... :|
For example because a,a2,a1 are all bi-dir pins what if:
a = output(High) and a2 = output(High)
At the node at the topmost tri-state buffer you would have a signal going into an output i.e. =>Boom<=. Same thing can be said about a1. I do not remember what this is called, but i do know such things break pins right?