#include <iostream>
    #include <vector>
    using namespace std;
    class ComponentClass
    { 
        public:
        virtual void traverse() = 0;
    };
    class LeafClass: public ComponentClass
    {
        int number;
        public:
        LeafClass(int num)
        {
            number = num;
        }
        void traverse()
        {
            cout << number << ' ';
        }
    };
    class CompositeClass: public ComponentClass
    {
        vector < ComponentClass * > children;
        public:
        void add(ComponentClass *ptr)
        {
            children.push_back(ptr);
        }
        void traverse()
        {
            for (int k = 0; k < children.size(); k++)
                children[k]->traverse();
        }
    };
    int main()
    {
        CompositeClass containers[6];
        for (int k = 0; k < 5; k++)
            for (int L = 0; L < 4; L++)
                containers[k].add(new LeafClass(k *4+L));
            for (int m = 1; m < 5; m++)
                containers[0].add(&(containers[m]));
            for (int n = 0; n < 5; n++)
            {
                containers[n].traverse();
                cout << endl;
            }
    }