稍微改了一下题面，加粗了平行于坐标轴。
by dottle @ 2022-09-08 20:01:52
zc
by wwkwwkwwk @ 2022-09-08 22:14:09
~~管理员的楼下的楼下~~
by hjczmf @ 2023-06-21 19:49:35