import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class ButterflyApplet extends Applet implements MouseListener {

	public void init ( ) {
		int n = getIntegerParam ("numbutterflies");
		Rectangle r = getBounds ( );
		Graphics g = getGraphics ( );
		this.addMouseListener (this);
		displayer = new ButterflyDisplayer (n, this, r);
		displayer.start ( );
	}
	
	private int getIntegerParam (String name) {
		String value = this.getParameter (name);
		if (value == "") {
			return 0;
		}
		try {
			return Integer.parseInt (value);
		} catch (Exception e) {
			return 0;
		}
	}
	
	public void mouseClicked (MouseEvent event) {
		// You complete this method.
		displayer.zap (x, y);
		repaint ( );
	}
	
	public void paint (Graphics g) {
		displayer.paint (g);
	}
		
	public void mouseReleased (MouseEvent event) {
	}
	
	public void mousePressed (MouseEvent event) {
	}

	public void mouseEntered (MouseEvent event) {
	}

	public void mouseExited (MouseEvent event) {
	}
	
	private ButterflyDisplayer displayer;
}

class ButterflyDisplayer extends Thread {

	public ButterflyDisplayer (int numButterflies, ButterflyApplet d, Rectangle r) {
		// Initialize the myButterflies reference here.
		whereImRunning = d;
		for (int k=0; k<numButterflies; k++) {
			int randomX = r.x + (int) (Math.random ( ) * r.width);
			int randomY = r.y + (int) (Math.random ( ) * r.height);
			// Add the new butterfly to myButterflies.
		}
	}
	
	private static Color randomColor ( ) {
		// Choose a random color from red, yellow, blue, green, and orange.
	}
	
	public void run ( ) {
		while (there are still butterflies remaining) {
			move ( );
			try {
			    Thread.sleep(200); // this slows the butterflies down
                        } catch( Exception e ) {
			}
			whereImRunning.repaint ( );
		}
	}
	
	final static int MAXMOVE = 10;	// maximum amount each butterfly flies at each move
	
	public synchronized void move ( ) {
		// for each Butterfly b in myButterflies, {
			int xDist = (int) (MAXMOVE*2 * Math.random ( )) - MAXMOVE;
			int yDist = (int) (MAXMOVE*2 * Math.random ( )) - MAXMOVE;
			b.move (xDist, yDist);
		}
	}
	
	public synchronized void paint (Graphics g) {
		// for each Butterfly b in myButterflies, {
			b.paint (g);
		}
	}
	
	public synchronized void zap (int x, int y) {
		// for each Butterfly b in myButterflies, {
			if (b.contains (x, y)) {
				// remove b from myButterflies;
			}
		}
	}
	
	private ButterflyCollection myButterflies;
	private ButterflyApplet whereImRunning;

}

class Butterfly {

	final static int BUTTERFLYSIZE = 30;	// size of a butterfly 
	
	public Butterfly (int x, int y, Color color) {
		myX = x;
		myY = y;
		myColor = color;
	}
	
	public void move (int xChange, int yChange) {
		myX += xChange;
		myY += yChange;
	}
	
	public boolean contains (int x, int y) {
		return x >= myX && x < myX+BUTTERFLYSIZE
			&& y >= myY && y < myY+BUTTERFLYSIZE;
	}
	
	public void paint (Graphics g) {
		Rectangle r = g.getClipBounds ( );
		if (myX < r.x) {
			myX += r.width;	// wrap around from left to right
		}
		if (myX >= r.x+r.width) {
			myX -= r.width;	// wrap around from right to left
		}
		if (myY < r.y) {
			myY += r.height;	// wrap around from top to bottom
		}
		if (myY >= r.y+r.width) {
			myY -= r.height;	// wrap around from bottom to top
		}
		g.setColor (myColor);
		g.fillRect (myX, myY, BUTTERFLYSIZE, BUTTERFLYSIZE);
	}	
	
	private int myX;
	private int myY;
	private Color myColor;
}