Why 7 lines turned into 2 lines after publish?

The sample txt file was uploaded here

sample for test

You can download it , copy , paste and publish it.

Are you adding line breaks via the ‘Text’ or ‘Visual’ editor?

• This reply was modified 7 years, 6 months ago by Andrew Nevins.

In text editor,i found that < p result in it,to remove < in < p ,newline is in good status,wordpress escape the < p in its own way.
In stackoverflow, all the white blanks at the beginning of line are treated as none.4 or more white blanks at the beginning of line can make the content in code status.