25. As shown in the figure, the sum of the numbers on the opposite faces of the cube is 7. If it is stipulated that the outside of side 2 is the front, and the cube is first flipped backward 15 times, then flipped to the right 30 times, each time flipping $90^{\circ}$, then the number on the top of the cube at this time is $\qquad$ .
answer: 2