prologues := 2;
beginfig(1);
  numeric u;
  u := .4cm;
  drawarrow (0, 0) -- (10u, 0);
  label.bot("V", (10u, 0));
  drawarrow (0, 0) -- (0, 10u);
  label.lft("p", (0, 10u));
  pair p, q, r, s;
  p := (4u, 8u);
  q := (9u, 3u);
  s := p shifted -(2u, 0);
  r := q shifted -(1.5u, 0);
  dotlabel.top("1", s);
  draw s .. p;
  dotlabel.top("2", p);
  draw p .. controls (((p + q)/2) shifted -(.5u, .5u)) ..  q;
  dotlabel.bot("3", q);
  draw r .. controls (((s + r)/2) shifted -(.5u, .5u)) ..  s;
  dotlabel.bot("4", r);
  draw q .. r;
  currentpicture := currentpicture shifted -llcorner currentpicture;
endfig;
end;