int x,y;

void setup(){
  size(300,300);
}
void loop(){
  background(255,255,255);

  rect(x,y,20+x,20+y);
}

void keyPressed(){
  if(key==UP){
    y =y-4;
  }
  if(key==DOWN){
    y =y+4;

  }
  if(key==RIGHT){
    x=x+4;
  }
  if(key==LEFT){
    x=x-4;
  }

}