[US] How many tree are visible ?

**As** Santa Clause in a Expediation
**I want to** know how many tree are visible from outside the grid
**So** I can build a very nice tree house

**More information**

* https://adventofcode.com/2022/day/8

**Test data**

```
30373
25512
65332
33549
35390
```

Will return **21** trees visible