I'd solved this yesterday, but net went down, and I've only just been able to log on..

Anyways congratulations to allamraju..

@feynmann

By the way was that observation you were talking about this

c0^2 + c1^2 + c2^2 + c3^2 = 1

And c0 . c2 + c1. c3 = 0

Anyway, that's how I got it..