The other day, my son asked me to build him a staircase using Lego-ish blocks. And I came up with something like this:

[![Staircase](https://i.stack.imgur.com/EzQUOm.jpg)](https://i.stack.imgur.com/EzQUOm.jpg)

Then my kid asked me for a program using the least number of bytes that generated a similar staircase in a computer screen. I am not that good at [code-golf](/questions/tagged/code-golf "show questions tagged 'code-golf'"), so I need your help. I need a program that:

* Receives a positive integer with the number of levels the staircase needs to have.
* Outputs a drawing of a staircase, with the pattern you see in the image.

The output will be in text format but the bricks can be distinguished one from another. For instance, you may use the '█' character as half a block and paint it in any color you want, or just choose any character of your choice.

Restrictions:

* Blocks need to be of three different colors, which will be used as long as possible (if input is 1 or 2 there are not enough blocks to use all three colors). If you want, you may use the '░▒▓' characters, for instance, or just select three different characters.
* No two blocks of the same color or pattern can be side to side in a single row.

My son does not really care about trailing spaces or new lines as long as a staircase is drawn.

Examples (sorry for the bad choice of characters):

```
Input: 1
Output:
██

Input: 2
Output:
██
 ▓▓

Input: 3
Output:
██
 ▓▓
██░░

Input: 5
Output:
██
 ██
██░░
 ██░░
██░░▓▓

```