%!PS
% Practicing PostScript

/s 20 string def

/drawArray{
  aload
  pop
  count{
    1 string cvs show
    20 0 rmoveto
  }repeat

} bind def

/pTree {
  /d exch def

  d 1 ge{
    21.6505 -12.5 rlineto
    0 -25 rlineto

    d cTree

    -21.6505 -12.5 rlineto
    -21.6505 12.5 rlineto

    d cTree

    0 25 rlineto
    21.6505 12.5 rlineto
  }if
} bind def
/cTree {
  /d exch def

  d 1 sub pTree

  /d d 1 add def
} bind def

% Set background color\
newpath
0.5 0.5 0.5 setrgbcolor clippath fill

1 1 1 setrgbcolor

300 400 translate

newpath
0 300 moveto

2 setlinewidth

/Courier-Bold findfont 20 scalefont setfont


3 pTree
-15 -30 rmoveto
[1 1] drawArray


stroke