<human>: The friend that lives with A is B. A and B switched their rooms because A asked B. A was initially told by landlord he can have the room that B lives in. But B argues that B was told the same by landlord. But anyway, eventually B agreed to move out to A's room to keep peace in the house. In the process of doing that, B's rent went up by about 2000 dollars in a year. B is a broke college student. So, one day, after they made the switch, B came to A and asked him to pay him 1000 dollars to his lost expense from living in his previous room. A said he will give as much as he can like a favor. They did not write a contract. A has been understanding this issue like he is doing B a favor since A practically does not owe B any money. A is giving some economical help to B because B asked for it. But in current situation, A already paid 400. A found himself in credit debt and told B that he cannot support the favor. Now, here is the problem. B is expecting 600 dollars back anytime in the future like A actually owes him money. What do you think A should do to address B's request regarding to 600?

Can you condense the text into three sentences or less?
<bot>: B, the roommate of A is asking 1000 dollars for switching rooms with him after he made the switch. Does A have obligation to give him 1000 dollars?