//if1.pde
void setup() {
  size(500,500);
  smooth();
  ellipseMode(CENTER);
}

void draw() {
  
  if (mouseX < 250) {
    stroke(255, 0, 0);
    
    if (mouseY < 250) {
      fill(0, 255, 0);
    } else {
      fill(0, 0, 255);
    }
    
  } else {
    stroke(0, 0, 255);
    
    if (mouseY < 250) {
      fill(255, 0, 0);
    } else {
      fill(255);
    }
  }
  ellipse(mouseX, mouseY, 50, 30);
}