What are the oxidation numbers in HOF?

Priority of determination of oxidation numbers involved in this question.
1. The oxidation number of F in compounds = -1 (no exception)
2. The oxidation number of H in compounds = +1 (with exception)
3. The oxidation number of O in compounds = -2 (with exception)

Since the oxidation of O is with exception and has the lowest priority, it should be determined at the last step.

In HOF :
The oxidation number of F = -1
The oxidation number of H = +1

As HF is a neutral compound, sum of oxidation numbers = 0
(Oxidation number of H) + (Oxidation number of O) + (Oxidation number of F) = 0
(+1) + (Oxidation number of O) + (-1) = 0
Oxidation number of O = 0