For the master version, we have six letters to place, and we know that I is third, so the pattern is _ _ I _ _ _ .

N is immediately before B, and K is after N --

-- but C is before I, which means there won't be room for NB before I. So the pattern is now _ _ INBK.

F isn't first, so it must be second. That means C must be first.

So the pattern is CFINBK.