public class BoboAndTheLockers
{
    public static void main(String[] args)
    {
        // true = open; false = closed
        boolean[] lockers = new boolean[1001];             
        // close all the lockers
        for (int i = 1; i <= 1000; i++)                    
            lockers[i] = false;

        for (int skip = 1; skip <= 1000; skip++)
        {
            System.out.println("Bobo is changing every " + skip + " lockers.");
            for (int locker = skip; locker < 1000; locker += skip)
                lockers[locker] = !lockers[locker];         
        }

        System.out.println("Bobo is bored" + " now so he's going home.");

        // count and list the open lockers
        String list = "";
        int openCount = 0;
        for (int i = 1; i <= 1000; i++)                    
            if (lockers[i])
            {
                openCount++;
                list += i + " ";
            }

        System.out.println("Bobo left " + openCount + " lockers open.");
        System.out.println("The open lockers are: " + list);
    }    
}