size(400, 400);
background(90,400,75);
stroke(74, 201, 4);
smooth();
rectMode(CENTER);

int shapeSize = 400;
int kindOfShape = 0;

while(shapeSize > 45){

if(kindOfShape == 0){

fill(220, 20, 185);
ellipse(175,175,shapeSize,shapeSize);
kindOfShape = 1;

}else{

fill(350, 50, 100);
rect(150,150,shapeSize,shapeSize);
kindOfShape = 0;

}

shapeSize = shapeSize - 7;

}