public class PackingDemo {
    public static int boxesNeeded(int itemCount, int capacity) {
        if (itemCount < 0 || itemCount > 10000) {
            throw new IllegalArgumentException("Item count must be 0 to 10000");
        }
        if (capacity < 1 || capacity > 1000) {
            throw new IllegalArgumentException("Capacity must be 1 to 1000");
        }
        if (itemCount == 0) {
            return 0;
        }
        return 1 + (itemCount - 1) / capacity;
    }

    public static void main(String[] args) {
        int itemCount = 29;
        int capacity = 12;
        int boxes = boxesNeeded(itemCount, capacity);
        System.out.println("Postcard packs: " + itemCount);
        System.out.println("Packs per box: " + capacity);
        System.out.println("Boxes needed: " + boxes);
    }
}