#include <cstdlib>
#include <iostream>

using namespace std;

struct node {
    public:
    node* next;
    node* prev;
    int data;
};

class linkedlist {

    public:
    node* current;
    node* first;

    linkedlist() {
    }
    ~linkedlist() {
        node* currentNode = first;
        do {
            node* temp = currentNode->next;
            delete currentNode;
            currentNode = temp;
        } while(currentNode->next);
    }
    void add(int string) {
        if(!first) {
            first = new node;
            current = first;
            current->next = NULL;
            current->data = string;
        } else {
            current->data = string;

            node* nextNode = new node;
            nextNode->data = 0;
            nextNode->next = NULL;

            current->next = nextNode;
            nextNode->prev = current;

            current = nextNode;
        }
    }
    int remove(int pos) {
        int count=0;
        node* currentNode = first;
        if(!first) return -1;

        if(!first->next) {
            int temp = first->data;
            delete first;
            first=NULL;
            current=NULL;
            return temp;
        }

        do {
            if(count++ == pos) {
                node* temp = currentNode->next;
                if(temp) {
                    temp->prev = currentNode->prev;
                    if(currentNode == first) {
                        first = currentNode->next;
                    }
                }
                (currentNode->prev)->next = temp;
                int retval = currentNode->data;
                delete currentNode;
                return retval;
            }
            currentNode = currentNode->next;
        } while(currentNode->next);
        return -1;
    }
    node* find(int string) {
        node* currentNode = first;
        do {
            if(string == currentNode->data) return currentNode;
            currentNode = currentNode->next;
        } while(currentNode->next);
        return NULL;
    }
    int size() {
        int count=0;
        node* currentNode = first;
        if(!first) return 0;
        do {
            count++;
            currentNode = currentNode->next;
        } while(currentNode->next);
        return count;
    }
    node* find_pos(int pos) {
        node* currentNode = first;
        do {
            if(!pos--) return currentNode;
            currentNode = currentNode->next;
        } while(currentNode->next);
    }
};