gap> Manifolds:=List(D,x->x[1]);;
gap> OrientableManifolds:=Filtered(Manifolds,m->Homology(m,3)=[0]);;
gap> NonOrientableManifolds:=Filtered(Manifolds,m->Homology(m,3)=[]);;
gap> Length(OrientableManifolds);
18
gap> Length(NonOrientableManifolds);
7
