mark post as read or unread

Hello guys,
I want to mark post as read or unread. For example user read a specific post,when user is going to read same post at that time user will get notification that user read that post before.
I want any notification like “seen button” or “unseen button” or anypopup message. Is there any soluton for that? or any plugin for that?
I have used mark as read plugin but it’s not working.
guys please help me.