Merging of two double linked lists

merge_doublelinkedlist.c

#include<stdio.h>
#include<stdlib.h>
int create();
int start();
int start1();
int a=0;
int x,k;
struct node
	{
	int data;
	struct node *prev,*post;
	};struct node *start2=NULL,*star1,*star2,*ptr,*new_node;
void main()
{
        start();
        start2=NULL;
        ptr=NULL;
        start1();
        ptr=star1;
        while(ptr->post!=NULL)
        {ptr=ptr->post;}
        ptr->post=star2;
        printf("\n\nMerged Double Linked list : \n\n");
        while(star1!=NULL)
        {printf("%d\n",star1->data);
         star1=star1->post;}


}
int create()
{
    int y;
    hi:
printf("\nEnter number of nodes you want to enter : ");
scanf("%d",&x);
char ch;
if(x>0){
        printf("\nEnter the data :\n\n");
while(x!=0)
    {
    scanf("%d",&y);
    new_node=(struct node*)malloc(sizeof(struct node));
    if(new_node==NULL)
        {
        printf("No Space");
        }
    else
        {
        if(start2==NULL)
            {
            start2=new_node;
            new_node->data=y;
            new_node->prev=NULL;
            new_node->post=NULL;
            }
        else
            {
           ptr=start2;
           while(ptr->post!=NULL)
            {
            ptr=ptr->post;
            }
            ptr->post=new_node;
            new_node->data=y;
            new_node->prev=new_node;
            new_node->post=NULL;
            }
        }
    x--;

}
a=a+1;
if(a==2){printf("\n%d'nd Linked list : \n\n",a);}else{
 printf("\n%d'st Linked list : \n\n",a);}
    new_node=start2;
	while(new_node!=NULL)
	{
		printf("%d\n",new_node->data);
		new_node=new_node->post;
	}
}
else
    {
        printf("\nNo node created...Enter y to create list again or else enter any other for exit... \n");
        scanf(" %c",&ch);
        if(ch=='y')
        {
            goto hi;
        }
        else
            {
            printf("\nNo merging will be performed without two linked lists \n");
            exit(0);

            }
    }
}
 int start()
{	create();
star1=start2;}

int start1()
{
create();
star2=start2;}