size(400, 400);
background(275,75,175);
stroke(250, 30, 100);
smooth();
fill(250, 250, 250);
int circleSize = 400;
// pink 250, 20, 20
// white 250, 250, 250
int DrawPink = 1;

while(circleSize > 50){
 if(DrawPink==1){
   fill(250, 30, 100);
   DrawPink = 0;
 }
 else{
   fill(250, 250, 250);
   DrawPink=1;
 }

 ellipse(200,200,circleSize,circleSize);
 circleSize = circleSize - 20;

}