// first version of a linked list class

#include <iostream>
#include <string>

using namespace std;

struct list_node {
    list_node(int init_data = 0, list_node * link = nullptr) {
        data = init_data;
        next = link;
    }

    int data;
    list_node * next;
};

class linked_list {
public:
    linked_list() {
        front = nullptr;
        back = nullptr;
        count = 0;
    }

    void add(int value) {
        if (count == 0) {
            front = new list_node(value);
            back = front;
            count = 1;
        } else {
            back->next = new list_node(value);
            count++;
            back = back->next;
        }
    }

    int size() const {
        return count;
    }

private:
    list_node * front;
    list_node * back;
    int count;
};

int main() {

    return 0;
}