program GrowingCircle;
uses Graph;

var
gd, gm, x, y, radius, increment: integer;

begin
gd := Detect;
InitGraph(gd, gm, '');

// Grow circle
radius := 10;
increment := 5;

repeat
x := GetMaxX div 2;
y := GetMaxY div 2;
setcolor(15);
setfillstyle(1, 15);
fillellipse(x, y, radius, radius);

Delay(100);
setcolor(0);
setfillstyle(1, 0);
fillellipse(x, y, radius, radius);
radius := radius + increment;

until radius > 300;

// Shrink circle
repeat
x := GetMaxX div 2;
y := GetMaxY div 2;
setcolor(15);
setfillstyle(1, 15);
fillellipse(x, y, radius, radius);

Delay(100);
setcolor(0);
setfillstyle(1, 0);
fillellipse(x, y, radius, radius);
radius := radius - increment;

until radius < 10;

CloseGraph;
end.