$_ = <>;
print "<HTML><TITLE>Literate program</TITLE>";
{s/@/$]=!$]/e and redo;
s/[^@]*/print $]?"$0":"<PRE>$0</PRE>";$]=!$];/e and redo;
$f=qr/\\(@)|\\(??{$f})/;
s/$f/$1/ and redo;}
print "</HTML>";