template <typename T>
struct Node
{
    T info;
    Node *next, *prev;
};

template<typename T>
class Queue
{
private:
    Node<T> *begin, *end;
    int queue_depth;

public:
    Queue() {
        begin = end = NULL;
        queue_depth = 0;
    }

    ~Queue() {
        delete[] begin;
    }

    Queue(const Queue &q) {
        Node<T>* cur = q.begin;
        this->begin = this->end = new Node<T>;
        this->begin->info = cur->info;
        this->queue_depth = 1;
        cur = cur->prev;
        while (cur != NULL) {
            this->push_back(cur->info);
            cur = cur->prev;
        }
    }

    Queue& operator =(const Queue &right) {
        if (this == &right)
            return *this;
        Node<T>* cur = right.begin;
        this->end = this->begin;
        this->begin->prev = NULL;
        this->begin->info = cur->info;
        cur = cur->prev;
        while (cur != NULL) {
            this->push_back(cur->info);
            cur = cur->prev;
        }
        return *this;
    }

    void push_front(T a) {
        Node<T>* cur = new Node<T>;
        if (!queue_depth) {
            begin = end = cur;
            cur->next = cur->prev = NULL;
            cur->info = a;
            queue_depth = 1;
            return;
        }
        begin->next = cur;
        cur->prev = begin;
        begin = cur;
        cur->next = NULL;
        cur->info = a;
        queue_depth++;
    }

    void push_back(T a) {
        Node<T>* cur = new Node<T>;
        if (!queue_depth) {
            begin = end = cur;
            cur->next = cur->prev = NULL;
            cur->info = a;
            queue_depth = 1;
            return;
        }
        end->prev = cur;
        cur->next = end;
        end = cur;
        cur->prev = NULL;
        cur->info = a;
        queue_depth++;
    }

    void print_begin() {
        Node<T>* cur = begin;
        while (cur != NULL) {
            cout << cur->info << endl;
            cur = cur->prev;
        }
    }

    void print_end() {
        Node<T>* cur = end;
        while (cur != NULL) {
            cout << cur->info << endl;
            cur = cur->next;
        }
    }

    void var5() {
        Node<T>* cur;
        while (begin->info % 5 == 0 && begin->info % 2 != 0) {
            begin = begin->prev;
            begin->next = NULL;
        }
        cur = begin;
        while (cur->prev->prev != NULL) {
            if (cur->prev->info % 5 == 0 && cur->prev->info % 2 != 0) {
                cur->prev = cur->prev->prev;
                cur->prev->next = cur;
            }
            else
                cur = cur->prev;
        }
        if (cur->prev->info % 5 == 0 && cur->prev->info % 2 != 0) {
            end = end->next;
            cur->prev = cur->prev->prev;
        }
    }

    void var11() {
        Node<T>* cur = begin;
        T sum = 0;
        while (cur != NULL) {
            sum += cur->info;
            cur = cur->prev;
        }
        begin->info = T(sum / queue_depth);
    }
};