beginfig(1)
   u = 1cm;
   pair shift;
   shift = (0u, 0u);
   draw (0,0) -- (-3u, -3u) -- (0, -6u) -- (3u, -3u) -- cycle shifted shift withpen pencircle scaled 2bp;
   draw (-8u,0) shifted shift withpen pencircle scaled 3bp;
   label.bot(btex 1 etex, (-8u,0));
   draw (-2u,0) shifted shift withpen pencircle scaled 3bp;
   label.bot(btex 2 etex, (-2u,0));
   draw (2u,-u) shifted shift withpen pencircle scaled 3bp;
   label.bot(btex 3 etex, (2u,-u));

   pickup pencircle scaled 5pt;
   drawdot(0, 0);
   pickup pencircle scaled 3pt;
   drawdot(0, 0) withcolor white;

   pickup pencircle scaled 0.5pt;

   drawarrow (0u,-8u)--(0u,3u) withcolor 0.5white;
   label.rt(btex $y$ etex, (0u, 3u));
   drawarrow (-10u,0u)--(4u,0u) withcolor 0.5white;
   label.bot(btex $x$ etex, (4u, 0u));
endfig;


end.