Number of lattice points in one unit cell of Face-centered tetragonal lattice

In Face-centered tetragonal ,8 lattice points at corners and 6 lattice points at face centers.A corner lattice point contributes one eight to the unit cell and a lattice point at face center contributes one half to the unit cell.Total number of lattice points per unit cell  =  8×18+6×12=1+3 =4