ps3.log

This is pdfTeX, Version 3.141592653-2.6-1.40.24 (TeX Live 2022) (preloaded format=pdflatex 2023.1.15)  26 APR 2023 23:28
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 restricted \write18 enabled.
 file:line:error style messages enabled.
 %&-line parsing enabled.
**ps3.tex
(./ps3.tex
LaTeX2e <2021-11-15> patch level 1
L3 programming layer <2022-02-24>
./ps3.tex:1: Undefined control sequence.
l.1 \section
            {PS3: Pythagoras Tree}\label{sec:ps3}
? 
./ps3.tex:1: Emergency stop.
l.1 
    
End of file on the terminal!

 
Here is how much of TeX's memory you used:
 16 strings out of 478268
 367 string characters out of 5846347
 289381 words of memory out of 5000000
 18325 multiletter control sequences out of 15000+600000
 469259 words of font info for 28 fonts, out of 8000000 for 9000
 1141 hyphenation exceptions out of 8191
 13i,0n,12p,84b,10s stack positions out of 10000i,1000n,20000p,200000b,200000s
./ps3.tex:1:  ==> Fatal error occurred, no output PDF file produced!