/************************************************************
 *  Name:
 *  NetID:
 *  Precept:
 *
 *  Description: Client to create and animate an array of N
 *  bouncing balls.
 *
 *  Example:
 *  $ java-introcs BouncingBalls 10
 ************************************************************/

public class BouncingBalls { 
    public static void main(String[] args) {

        // read number of bouncing balls from command-line
        int n = ___________________________ 

        // initialze standard drawing
        StdDraw.setXscale(-1.0, 1.0);
        StdDraw.setYscale(-1.0, 1.0);
        StdDraw.enableDoubleBuffering();

        // create an array of n balls
        Ball[] balls = _____________________
        for (int i = 0; i < n; i++)
            balls[i] = ______________________

        // do the animation loop
        while(true) {

            // gray background
            StdDraw.clear(StdDraw.GRAY);

            // draw and move n black balls
            StdDraw.setPenColor(StdDraw.BLACK);
            for (int i = 0; i < ____; i++) {
               _____________________________________
               _____________________________________
            }
            StdDraw.show();
            StdDraw.pause(20);
        }
    }
}