public class Balls {

    enum Color {green, red};

    public static void main (String[] param) {
        // for debugging
    }
   
    public static void reorder (Color[] balls) {
        int redBallCount = 0;

        // count how many red balls there is
        for (int i = 0; i < balls.length; i++) {
            if (balls[i] == Color.red) {
                redBallCount++;
            }
        }


        // If all balls are red or green then just return
        if (redBallCount == balls.length) {
            return;
        } else if (redBallCount == 0) {
            return;
        }

        // replace the contents of the array with new colors that are in correct order
        for (int i = 0; i < redBallCount; i++) {
            balls[i] = Color.red;
        }
        for (int i = redBallCount; i < balls.length; i++) {
            balls[i] = Color.green;
        }
    }
}