Given a cube ABCDA1B1C1D1 with lower base ABCD, upper base A1B1C1D1 and the lateral edges AA1,BB1,CC1 and DD1; M and M1 are the centers of the faces ABCD and A1B1C1D1 respectively. O is apoint on line MM1, such that
OA+OB+OC+OD=OM1, then OM=λOM1 is λ=