It is exactly the same as my answer without the little error.
I accept that you found it independently though.
It was a 'thank you for answering' that I was looking for.
A further comment would have been good too.
If you had bothered to look at imy answer hard enough to find my little error that would have gone down really well.
We do not answer these ONLY to amuse ourselves.
Anyway, I am glad that you know how to do them now.