Merging of two Linked lists

merge_linkedlist.c

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

}
void create()
{struct node *nn;
	hi:

	printf("\nEnter number of nodes you want : ");
	char ch;
	int x,y;
	scanf("%d",&y);
	if(y>0){
	printf("\nEnter the data : \n");
	while(y!=0)
	{
	    scanf("%d",&x);
		nn=(struct node*) malloc(sizeof(struct node));
		if(nn==NULL)
		{
			printf("no space");
		}
		else
		{
			if(start==NULL)
			{
				start=nn;
				nn->data=x;
				nn->adr=NULL;
			}
			else
			{
				ptr=start;
				while(ptr->adr!=NULL)
				{
					ptr=ptr->adr;
				}
				ptr->adr=nn;
				nn->data=x;
				nn->adr=NULL;
			}
		}
		y--;

	}
	ptr=start;
	a=a+1;
	if(a==1){
	printf("\n%d'st Linked list : \n",a);}
	else{printf("\n%d'nd Linked list : \n",a);}
        while(ptr!=NULL)
          { printf("%d\n",ptr->data);
            ptr=ptr->adr;
         }
     printf("\n");
}
        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);

            }
    }
}
 void start1()
{	create();
	star1=start;
  }
void start2()
{
create();
star2=start;
 }