class FPS {
	long lastTime;
	double fps;
	
	FPS(double fps) {
		lastTime = System.currentTimeMillis();
		this.fps = fps;
	}
	
	double delay() {
		long d = System.currentTimeMillis() - lastTime;
		try {
			Thread.sleep((int)(1000/fps) - d);
		} catch (Exception e) {}
		lastTime = System.currentTimeMillis();
		return d/(1000/fps);
	}
}