She can not fit more than twenty rows in the class so anything equal to twenty or less (not including zero or negative numbers) would be fine. We don't have a limit for how many chairs in a row so I'm answering assuming that is not a problem so 20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2, or 1 row(s) would be possible