### Missing Numbers

Given an array containing all the numbers from 1 to n except two, find the two missing numbers.

### Example

 - `missing([]int{4, 2, 3}) = []int{1, 5}`
 - `missing([]int{1, 2, 3, 4}) = []int{5, 6}`

### Run tests with benchmarks

```
go test -bench .
```
