Minho has N boxes. The pile grew too large, so he wants to tidy it up, but he finds ordinary tidying dull and set two rules to make it more fun.
- Let Vx be the size of box x and Vy the size of box y. You can put box x inside box y if Vy≥2Vx.
- If box x is inside box y, then box y cannot be put inside another box. A box holds at most one other box.
Only a box that is not inside another box is visible. Tidy the boxes under these rules so that the number of visible boxes is as small as possible, and report that minimum.