#include <iostream>

using namespace std;

struct Node

{

    int data;

    Node *next;

    Node(int val)

    {

        data = val;

        next = NULL;

    }

};

void insertAtTail(Node *&head, int val)

{

    Node *n = new Node(val);

    Node *temp = head;

    if (temp == NULL)

    {

        head = n;

        return;

    }

    while (temp->next != NULL)

    {

        temp = temp->next;

    }

    temp->next = n;

}

void deleteAtTail(Node *&head)

{

    Node *temp = head;

    while (temp->next->next != NULL)

    {

        temp = temp->next;

    }

    delete temp->next->next;

    temp->next = NULL;

}

void deleteAtHead(Node *&head)

{

    Node *temp = head;

    head = temp->next;

    delete temp;

}

void deleteAtPos(Node *&head, int pos)

{

    Node *temp = head;

    Node *temp1 = NULL;

    int count = 0;

    while (temp != NULL && count != pos)

    {

        count++;

        temp1 = temp;

        temp = temp->next;

    }

    temp1->next = temp->next;

    delete temp;

}

int main()

{ 

   Node *head = NULL;

    insertAtTail(head, 1);

    insertAtTail(head, 2);

    insertAtTail(head, 3);

    deleteAtTail(head);

  )