#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>

struct Node {
  struct Node *ptr;
  int data;
};

struct Node *head = NULL;

struct Node *createNode(int v) {
  struct Node *new = (struct Node *)malloc(sizeof(struct Node));
  new->data = v;
  new->ptr = NULL;
  return new;
}

void insertend(int v, struct Node *new) {
  if (head == NULL) {
    head = new;
    return;
  }
  struct Node *temp = head;
  while (temp->ptr != NULL) {
    temp = temp->ptr;
  }
  temp->ptr = new;
  new->ptr = NULL;
}

void insertstart(int v, struct Node *new) {
  struct Node *temp = head;
  head = new;
  new->ptr = temp;
}

void insert(int v, struct Node *new, int x) {
  struct Node *temp = head;
  int w = 0;
  while (temp->ptr != NULL && w < x) {
    temp = temp->ptr;
    w++;
  }
  struct Node *temp2 = temp->ptr;
  temp->ptr = new;
  new->ptr = temp2;
}
void display() {
  struct Node *temp = head;
  while (temp != NULL) {
    printf("%d \n", temp->data);
    temp = temp->ptr;
  }
}
void deletestart() {
  if (head == NULL) {
    printf("list empty");
    return;
  }
  struct Node *temp = head;

  head = temp->ptr;
  free(temp);
}
void deletelast() {
  if (head == NULL) {
    printf("list empty");
    return;
  } else {
    struct Node *temp = head;
    struct Node *prev = NULL;
    while (temp->ptr != NULL) {
      prev = temp;
      temp = temp->ptr;
    }
    prev->ptr = NULL;
    free(temp);
  }
}

void deletex(int x) {
  if (head == NULL) {
    printf("list empty");
    return;
  } else {
    struct Node *temp = head;
    struct Node *prev = NULL;
    int k = 0;
    while (temp->ptr != NULL && k < x - 1) {
      prev = temp;
      temp = temp->ptr;
      k++;
    }
    // If x is beyond the last node
    if (temp == NULL) {
      printf("Position %d not found\n", x);
      return;
    }
    prev->ptr = temp->ptr;
    free(temp);
  }
}
int main() {
  struct Node *first = createNode(5);
  insertstart(5, first);
  display();
  struct Node *second = createNode(6);
  insertend(6, second);
  display();
  deletelast();
  display();
}