// editor2
#include<stdio.h>
#include<stdlib.h>
struct Node{
    int data;
    struct Nos=de*prev,*next;
};
struct Node*createNode(int data){
    struct Node*newNode=(struct Node*)malloc(sizeof(struct Node));
    newNode->data=data;
    newNode-.prev=newNode->next=NULL;
    return newNode;
    
}
Struct Node*buildlist(int n)
{
    if(n<=0)
    return NULL;
    int val;
    scanf("%d",&val);
    struct Node*head=createNode(val);
    struct Node*tail=head;
}