#include <iostream>
using namespace std;

struct node {
    int info;
    node * next;
};

struct SLL {
    node * head, * tail;
    void init() {
        head = NULL;
        tail = NULL;
    }

    void insertFront(int x) {
        node * new_node = new node;
        new_node->info = x;

        if(head == NULL) {
            head = new_node;
            tail = head;
            tail->next = head;
        }
        else {
            new_node->next = head;
            head = new_node;
            tail->next = head;
        }
    }

    void insertEnd(int x) {
        node * new_node = new node;
        new_node->info = x;

        if(head == NULL) {
            head = new_node;
            tail = head;
            tail->next = head;
        }
        else {
            tail->next = new_node;
            tail = new_node;
            tail->next = head;
        }
    }

    void deleteFront() {
        if(head != NULL) {
            if(head->next == head) {
                delete head;
                head = NULL;
                tail = NULL;
            }
            else {
                node * tmp = head;
                head = head->next;
                tail->next = head;
                delete tmp;

            }
        }
    }

    void deleteEnd() {
        if(head != NULL) {
            if(head->next == head) {
                delete head;
                head = NULL;
                tail = NULL;
            }
            else {
                node * tmp = head;
                while(tmp->next != tail) {
                    tmp = tmp->next;
                }
                tmp->next = head;
                delete tail;
                tail = tmp;
            }
        }
    }

    void deleteNode(int x) {
        if(head != NULL) {
            if(head->info == x) {
                deleteFront();
            }
            else if(tail->info == x) {
                deleteEnd();
            }
            else {
                node * tmp = head;
                node * prev = NULL;

                while(tmp != NULL and tmp->info != x) {
                    prev = tmp;
                    tmp = tmp->next;
                }
                prev->next = tmp->next;
                delete tmp;
            }
        }
    }
    void deleteNode(node *  x) {
        if(head != NULL) {
            if(head == x) {
                deleteFront();
            }
            else if(tail == x) {
                deleteEnd();
            }
            else {
                node * tmp = head;
                node * prev = NULL;

                while(tmp != NULL and tmp != x) {
                    prev = tmp;
                    tmp = tmp->next;
                }
                prev->next = tmp->next;
                delete tmp;
            }
        }
    }

    void deleteAll() {
        while(head != NULL) {
            deleteEnd();
        }
    }
    void print() {
        node * tmp = head;

        while(tmp != tail) {
            cout << tmp->info << "-->";
            tmp = tmp->next;

        }
        cout << tail->info << "-->";
        tmp = tmp->next;
        while(tmp != tail) {
            cout << tmp->info << "-->";
            tmp = tmp->next;

        }
        cout << tmp->info;
        cout << endl;
    }
};
int main() {

    SLL sll;
    sll.init();

    sll.insertFront(1);
    sll.insertFront(2);
    sll.insertFront(3);


    sll.insertEnd(4);
    sll.insertEnd(5);
    sll.insertEnd(6);
    sll.print();

    sll.deleteNode(1);

    sll.print();


return 0;

}