Please solve the programming task below using a self-contained code snippet in a markdown code block.

You have a cubic storeroom where the width, length, and height of the room are all equal to n units. You are asked to place n boxes in this room where each box is a cube of unit side length. There are however some rules to placing the boxes:

You can place the boxes anywhere on the floor.
If box x is placed on top of the box y, then each side of the four vertical sides of the box y must either be adjacent to another box or to a wall.

Given an integer n, return the minimum possible number of boxes touching the floor.
 
Please complete the following python code precisely:
```python
class Solution:
    def minimumBoxes(self, n: int) -> int:
```