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.

Example 1:

    Input: n = 3
    Output: 3
    Explanation: The figure above is for the placement of the three boxes.
    These boxes are placed in the corner of the room, where the corner is on the left side.

Example 2:

    Input: n = 4
    Output: 3
    Explanation: The figure above is for the placement of the four boxes.
    These boxes are placed in the corner of the room, where the corner is on the left side.

Example 3:

    Input: n = 10
    Output: 6
    Explanation: The figure above is for the placement of the ten boxes.
    These boxes are placed in the corner of the room, where the corner is on the back side.

Constraints:

- `1 <= n <= 109`