#include <iostream>
using namespace std;

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

struct SinglyLinkedList {
    node * head;

    void init() {
        head = NULL;
    }

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

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


    void insertBack(int x) {
        node * new_node = new node;
        new_node->info = x;
        new_node->next = NULL;

        if(head == NULL) {
            new_node = head;
        }
        else {
            node * tmp = head;
            while(tmp->next != NULL) {
                tmp = tmp->next;
            }
            tmp->next = new_node;
        }
    }

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

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

    void deleteAll() {
        while(head != NULL) {
            deleteFront();
        }
    }

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

                while(tmp != NULL && 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 {
                node * tmp = head;
                node * prev = NULL;

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

                prev->next = tmp->next;
                delete tmp;
            }
        }
    }

    void print() {
        node * tmp = head;
        while(tmp != NULL) {
            cout << tmp->info << " --> ";
            tmp = tmp->next;
        }
        cout << endl;
    }


};


int main() {

    SinglyLinkedList sll;

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

    sll.insertBack(4);
    sll.insertBack(5);

    sll.print();

    sll.deleteNode(1);

    sll.print();

    return 0;
}