uses graph,crt;
var
 j,gd,gm,i,c,R,T,dLx,dLy,MaxX,MaxY,Lx,Ly,r0,t0:integer;
 x,y,k:array [1..1000] of integer;
 b:boolean;
Begin
 randomize;
 gd:=detect;
 initgraph(gd,gm,'d:\tp7\units\');
 c:=6;
 r0:=12;
 MaxX:=GetMaxX;
 MaxY:=GetMaxY;
 for i:=1 to 1000 do
  begin
   R:=Random(50);
   T:=Random(360);
   x[i]:=50+Round(7*Sqrt(R)*Cos(Pi*T/180));
   y[i]:=50+Round(7*Sqrt(R)*Sin(Pi*T/180));
   putpixel(x[i],y[i],c);
  end;
 Lx:=10;
 Ly:=Round(SQRT(sqr(r0)-sqr(Lx)));
 REPEAT
  Repeat
   b:=false;
   i:=0;
   repeat
    Inc(i);
    dLx:=Round(0.4*Abs(Lx))-Random(Round(0.4*Abs(Lx)));
    dLy:=Round(0.4*Abs(Lx))-Random(Round(0.4*Abs(Lx)));
    putpixel(x[i],y[i],0);
    x[i]:=x[i]+Lx+dLx;
    y[i]:=y[i]+Ly+dLy;
    If (x[i]<0) or (x[i]>MaxX) or (y[i]<0) or (y[i]>MaxY) then
     begin
      b:=true;
      x[i]:=x[i]-Lx-dLx;
      y[i]:=y[i]-Ly-dLy;
      putpixel(x[i],y[i],c);
     end else
    putpixel(x[i],y[i],c);
    delay(1);
   until b or (i=1000);
  Until b or KeyPressed;
  If KeyPressed then
    begin
    CloseGraph;
    Halt(0);
   end;
  t0:=Random(360);
  Lx:=Round(r0*Cos(t0*Pi/180));
  Ly:=Round(r0*Sin(t0*Pi/180));
 UNTIL 0=1;
End.