You have a cubic storeroom with dimensions n x n x n units. Your task is to arrange n boxes in this room, where each box is a cube with side length 1 unit. However, there are certain rules for placing the boxes: 1. The boxes can be placed anywhere on the floor of the room. 2. If box x is placed on top of box y, then each side of the four vertical sides of box y must either be adjacent to another box or to a wall. Given an integer n, you need to determine the minimum number of boxes that must touch the floor.