This is pdfTeX, Version 3.141592653-2.6-1.40.22 (TeX Live 2021 on Slackware) (preloaded format=pdflatex 2021.10.13)  28 NOV 2021 07:12
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**res1.tex
(./res1.tex
LaTeX2e <2020-10-01> patch level 4
L3 programming layer <2021-02-18>

./res1.tex:1: LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
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l.1 <
     !doctype html>
? 
./res1.tex:1: Emergency stop.
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l.1 <
     !doctype html>
You're in trouble here.  Try typing  <return>  to proceed.
If that doesn't work, type  X <return>  to quit.

 
Here is how much of TeX's memory you used:
 17 strings out of 478994
 517 string characters out of 5864715
 283044 words of memory out of 5000000
 17602 multiletter control sequences out of 15000+600000
 403430 words of font info for 27 fonts, out of 8000000 for 9000
 1141 hyphenation exceptions out of 8191
 13i,0n,15p,55b,14s stack positions out of 5000i,500n,10000p,200000b,80000s
./res1.tex:1:  ==> Fatal error occurred, no output PDF file produced!