insert first (doubly)

#include<stdio.h>
#include<stdlib.h>
typedef struct Node
{
  int a;
  struct Node *next,*prev;
  }node;
node*head=NULL,*tail=NULL;

void insert_first (int an)
{
node*N=(node*)malloc(sizeof(node));
N->a=an;

N->next=NULL;
N->prev=NULL;

if(head==NULL){
   head=N;
   tail=N;
}
else{
   head->prev=N;
   N->next=head;
   head=N;
}
}
void display_first()
{
    node*list=head;
    if(head==NULL)
    {
        printf("No Data Available\n");


    }
    else
    {
        while(list!=NULL)
        {
            printf("%d\n",list->a);
            list=list->next;
        }
    }
    }
int main(){
int n,x,i;
    head=NULL;
    printf("Input the Number of Node:");
    scanf("%d",&n);
    for(i=0;i<n;i++){
        scanf("%d",&x);
        insert_first(x);

    }
display_first();
    return 0;
}