interface Iterator<T> {
    boolean hasNext();
    T next();
}

interface IterableCollection<T> {
    Iterator<T> createIterator();
}

class BrowseHistory implements IterableCollection<String> {
    private String[] urls = new String[10];
    private int count = 0;

    void push(String url) {
        urls[count++] = url;
    }

    String pop() {
        return urls[--count];
    }

    public Iterator<String> createIterator() {
        return new HistoryIterator(this);
    }

    private class HistoryIterator implements Iterator<String> {
        private BrowseHistory history;
        private int index = 0;

        HistoryIterator(BrowseHistory history) {
            this.history = history;
        }

        public boolean hasNext() {
            return index < history.count;
        }

        public String next() {
            return history.urls[index++];
        }
    }
}

public static void main(String[] args) {
    BrowseHistory history = new BrowseHistory();
    history.push("a.com");
    history.push("b.com");
    history.push("c.com");

    Iterator<String> iterator = history.createIterator();
    while (iterator.hasNext()) {
        System.out.println(iterator.next());
    }
}