tex-compile pdflatex can't find input tex after removing auctex

[silencej]

As the title says, after i remove auctex, restarte, tex-compile ->
pdflatex, the GnuEmacs complains an error in tex-shell:

[code]
Babel <v3.8l> and hyphenation patterns for english, usenglishmax,
dumylang, noh
yphenation, pinyin, loaded.

! I can't find file `main.tex'.
<*> \nonstopmode\input main.tex

(Press Enter to retry, or Control-D to exit)
Please type another input file name
! Emergency stop.
<*> \nonstopmode\input main.tex

!  ==> Fatal error occurred, no output PDF file produced!
Transcript written on texput.log.
[\code]

While i re-install auctex, use C-c C-t C-p to compile in pdflatex, the
compilation works.

So i think it's a problem left by AUCTeX. However, "apt-get purge
auctex" doesn't help either.