I am using powershell, if that matters.

Let's say I have

```
$s = "One two (three) four \(five\) six (\(seven\)) eight"

```

I want a regex that will return 

```
 three
 (seven)

```

I need all matches, and I know how PowerShell stores the matches in $matches, similar to perl's $1 $2 $3 (but that's the easy part).