So the angular position for constructive fringes is
d \sin \theta = m \lambda = (2m) \frac{\lambda}{2}, \qquad m=0, \pm 1, \pm 2, \ldots
whereas for destructive fringes we have
d \sin \theta = m \lambda = (2m+1) \frac{\lambda}{2}, \qquad m=0, \pm 1, \pm 2, \ldots
I can see that ##m##...