I can only copy all the other answers. Do not pull the seatpost too far up.
There is a minimum insert mark on the seastpost. The reason is the post is not vertical so while sitting on it you are bending the post. When the post is mounted too shallow, it can bend or break the frame.
I cannot recommend using longer seatpost either, because longer post means higher bending momentum. You can bend or break the post itself, damage the frame or both.
Wery nasty injuries come from seat and seatpost failures!
If you need to pull the saddle up that much, the frame is too small for you. I would strongly recommend giving the bike to someone smaller tha you are and getting yourself bike that fits you.