\parskip=1pt plus 1pt minus 0.3pt
\rightskip=2em
\itemcount=0
+\smallskip
}
\def\endalgo{\interlistskip\endgroup}
\def\algopar{\par
\leavevmode
}
\def\algoitem{
-\ifnum\itemcount=0\smallskip\fi
\algopar\advance\itemcount by 1
\hbox to 2em{\hss \the\itemcount. }%
\futurelet\next\algoitemh}