The thing is that if you use __DATA__, perl automatically seeks to the beginning of the DATA-section. But at the same time it sets the DATA-filehandle to the current file, so if you seek it yourself, you actually seek the source code itself.

I learned this from TheDamians SelfGOL.

And BTW, your solution is correct (and very well written, IMO)

The only thing worth mentioning is that
seek+print
is actually the same as
seek print
as the + is used as the unary plus in front of a term, basically having no effect on anything.

--
#!/usr/bin/perl -w just another perl hacker
print+seek(DATA,$=*.3,@-)?~~<DATA>:$:__DATA__