12. Ivan the Tsarevich's Arrows (from 8th grade. 3 points). Ivan the Tsarevich is learning to shoot a bow. He put 14 arrows in his quiver and went to shoot at pine cones in the forest. He knocks down a pine cone with a probability of 0.1, and for each pine cone he knocks down, the Frog-Princess gives him 3 more arrows. Ivan the Tsarevich shoots until he runs out of arrows. Find the expected number of shots Ivan the Tsarevich will make.