In the following reaction sequence, major products X and Y are acyclic monomers.

500 mol of X completely reacts with 500 mol of Y to give 1 mol of a single biodegradable acyclic copolymer Z as the only product. The amount of Z formed in grams is ___.

Given: Atomic mass (in amu): H : 1, C : 12, N : 14, O : 16, Br : 80