<image>Mr. Zhang's birthday is one of the following 10 dates, Mr. Zhang told Student A the month he was born, and Student B the date he was born. Mr. Zhang then asked them if they knew his birthday:
A said: If I don't know, then B definitely doesn't know either.
B said: I didn't know at first, but now I know.
A then said: Oh, now I know as well. Mr. Zhang's birthday is ____month ____day.
