|A past log can be perused from here.|
The number of a past log is put in for seeing a past log, and it pushes "it sees." A past log is so new that a number is large.
The present log will be seen if it puts in with x.
What overflowed with the present logs goes into the newest past log one by one.
The newest past log may have little number of cases.
There is none of all past logs.
It cannot contribute/delete in a past log.