Element B forms CCP structure and A occupy half of the octahedral voids while oxygen atoms occupy all the tetrahedral voids. The structure is ${\mathrm{A}}_{\mathrm{x}}{\mathrm{B}}_{\mathrm{y}}{\mathrm{O}}_{\mathrm{z}}$ then $\mathrm{x}+\mathrm{y}+\mathrm{z}$ is (simplest formula)