change color of screen based on mouse click

gistfile1.pde

//tests if mouse button is pressed and where the mouse is on the screen
//changes background color accordingly

void setup(){
  size(500,500);
  background(255,0,0);
}

void draw(){
  //top left quater of screen && mouse pressed
  if(mousePressed && mouseX > 0 && mouseY > 0 && mouseX < 250 && mouseY < 250){
    background(0,255,0);
  }
  //top right quarter of screen && mouse pressed
  else if(mousePressed && mouseX > 250 && mouseY > 0 && mouseX < 500 && mouseY < 250){
    background(0,0,255);
  }
  //anything else
  else{
    background(255,0,0);
  }
}