var x1, y1, x2, y2, checkx, checky : int
loop
    checky := Rand.Int (0, maxy)
    checkx := Rand.Int (0, maxx)
    x1 := Rand.Int (checkx, maxx)
    y1 := Rand.Int (checky, maxy)
    x2 := Rand.Int (checkx, maxx)
    y2 := Rand.Int (checky, maxy)
    Draw.Dot (x1, y1, black)
    Draw.Dot (x2, y2, black)
    Draw.Dot (x1, y2, black)
    Draw.Dot (x2, y1, black)
    exit when hasch
end loop
for x : 1 .. maxx
    drawdot(x, (round(1/(x/10000))), green)
    drawline(x, (round(1/(x/10000))), x+1, (round(1/((x+1)/10000))), brightred)
end for

% output at http://i.imgur.com/9eDIcsb.png