Both men are Liars.
First, from A's assertion, it can be deduced that B must be a Liar. If A was a Knight, then B would have to lie. And if A was a Liar, then it must be false that B would say so, so B would also be a Liar.
Since B is a Liar in any case, if he says A is truthful, then A must be a Liar too. |