# Shape Area

Below we will define an n-interesting polygon. Your task is to find the area of a polygon for a given n

A 1-interesting polygon is just a square with a side of length 1. An n-interesting polygon is obtained by taking the n - 1-interesting polygon and appending 1-interesting polygons to its rim, side by side. You can see the 1-, 2-, 3- and 4-interesting polygons in the picture below.

## Example

- For n = 2, the output should be solution(n) = 5;
- For n = 3, the output should be solution(n) = 13.

## Input

integer n. Guaranteed constraints: 1 ≤ n < 104.

## Output

The area of the n-interesting polygon.

## Solution

## Solution

rust

```
fn solution(n: i32) -> i32 {
n.pow(2) + (n-1).pow(2)
}
```