Doubly linked list in CPP

DLL.cpp

#include <iostream>
using namespace std;

struct Node{
  struct Node *prev;
  int data;
  struct Node *next;
}*start=NULL,*last=NULL;

void insert(int ele){
  struct Node *p = start,*temp;
  if(p==NULL){
    temp = new Node;
    temp->data = ele;
    temp->prev = NULL;
    temp->next = NULL;
    start=last=temp;
  }else{
    temp = new Node;
    temp->data = ele;
    temp->next = last->next;
    last -> next = temp;
    temp->prev = last;
    last = temp;
  }
}

void display(){
  struct Node *p = start;
  while(p){
    cout << p->data << " == ";
    p=p->next;
  }
}

int count(){
  int count = 0;
  struct Node *p = start;
  while(p){
    count++;
    p=p->next;
  }
  return count;
}

void insert_at_beg(int ele){
  if(start==NULL){
    insert(ele);
    return;
  }
  struct Node *temp;
  temp = new Node;
  temp->data = ele;
  temp -> next = start;
  start -> prev = temp;
  temp->prev = NULL;
  start = temp;
}

void insert_at(int pos,int ele){
  struct Node *p = start,*temp;
  if(pos <= 1){
    insert_at_beg(ele);
  }
  else if(pos > count()){
    insert(ele);
  }
  else{
    for(int i=1;i<pos-1;i++){
      p=p->next;
    }
    temp = new Node;
    temp->data = ele;
    temp -> next = p->next;
    p->next = temp;
    temp -> prev = p;
  }
}

void del_at(int pos){
  struct Node *p = start,*q=NULL;
  if(pos<1 || pos>count() || start==NULL){
    cout << endl << "Not Possible!" << endl;
    return;
  }
  if(pos == 1){
    start = p->next;
    p->next->prev = NULL;
    delete p;
  }
  else if(pos < count()){
    for(int i=1;i<=pos-1;i++){
      q=p;
      p=p->next;
    }
    q->next = p->next;
    p->next->prev = q;
    delete p;
  }
}

int main(){
  for(int i=1;i<=10;i++){
    insert(i);
  }
  display();
  del_at(3);
  display();
  return 0;
}