Assume that you started to store items in progressively expanding square location, like this for the first 9 numbers:
```
05 04 03
06 01 02
07 08 09
```
And like this for the expanding to include up to the first 25 numbers:
```
17 16 15 14 13
18 05 04 03 12
19 06 01 02 11
20 07 08 09 10
21 22 23 24 25
```
You might easily notice that the first - and innermost - layer containes only one number (`01`), the second one  - immediately around it - contains 8 numbers (number in the `02-09` range) and so on.
Your task is to create a function that given a number `n` simply returns the number of layers required to store up to `n` (included).
```python
layers(1) == 1
layers(5) == 2
layers(25) == 3
layers(30) == 4
layers(50) == 5
```
**Fair warning:** you will always and only get positive integers, but be ready for bigger numbers in the tests!
If you had fun with this, also try some follow up kata: [progressive spiral number branch](https://www.codewars.com/kata/progressive-spiral-number-branch/) and [progressive spiral number distance](https://www.codewars.com/kata/progressive-spiral-number-distance/).
*[Base idea taken from [here](http://adventofcode.com/2017/day/3)]*
def layers(n):
    return int(((n - 1)**0.5 + 1) // 2) + 1 
def layers(n):
    return int(((n - 1)**0.5 + 1) // 2) + 1 