complexity theory – Solve the recursive function $T(n) = T(sqrt{n}) + T(n – sqrt{n}) + theta(n)$

in one of my college assignments i came up with the following recursive function which I’m ask to solve:
$T(n) = T(sqrt{n}) + T(n – sqrt{n}) + theta(n)$

I could not use master method on it and it is not an LHR either.
I assume this must have something to do with recursion tree but i cant figure the relation if so.