How to determine the execution flows of RxJava operators in a chain

It is necessary to understand in which threads create, map, and subscribe will operate if the given code fragment is run from the main (UI) thread.

Observable.create<Int> { }
    .map { }
    .subscribeOn(Schedulers.io())
    .observeOn(Schedulers.computation())
    .map { }
    .subscribe { }