Ask: "You don't think this is right", Answer:"No, I don't". What does that mean?

Ask: "You don't think this is right", Answer:"No, I don't". What does that
mean?

English sentences can be very fascinating... or downright confusing,
depends on how you look at it.
For example, if A asks B:"You don't think the Josh is right on this, do
you", and B answers:"No, I don't" and then FULL STOP. No further
clarification will come from B.
So, how should we interpret B's answer? Is B thinking that Josh is right,
or is B thinking that Josh is wrong? Is B agreeing with A, or disagreeing?