// editor4
#include<stdio.h>
#include<stdlib.h>
struct node{
    int data;
    struct node*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;
}
void insertend(struct node**head,int data)
{
    struct node*newnode=createnode(data);
    if(*head==NULL){
        *head=newnode;
        return;
    }
    struct node*temp=*head;
    while(temp->next) temp=temp->next;
    temp->next=newnode;
    newnode->prev=temp;
}
struct node*merge(struct node*head1,struct node*head2)
{
    if(!head1)return head2;
    if(!head2)return head1;
    struct node*head=NULL,*tail=NULL;
    while(head1&&head2)
    {
        struct node*temp;
        if(head1->data<=head2->data){
            
        }
    }
}

}
}
}