uses graph, crt;
var d, m, x, y, i, j, k:integer;
begin
d:=detect; initgraph(d, m, '');
 x:=100;
 y:=100;
{cleardevice;}
repeat
for j:=10 to 25 do
begin
     setcolor(green);
     circle(x, y, 25);
     delay(100);
     setcolor(black);
     circle(x, y, 25);
     x:=x+5;
     y:=y+5;
end;
for k:=25 to 50 do
begin
     setcolor(green);
     circle(x, y, 25);
     delay(100);
     setcolor(black);
     circle(x, y, 25);
     x:=x+5;
     y:=y-5;
end;
for i:=10 to 50 do
begin
     setcolor(green);
     circle(x, y, 25);
     delay(75);
     setcolor(black);
     circle(x, y, 25);
     x:=x-5;
     y:=y+1;
end;
until keypressed;
readln;
end.