Implementation of Merging of Two Linked List(Ascending orde)

#include<conio.h>
#include<stdlib.h>
#include<stdio.h>

void add(struct node **,int);
void display(struct node*);
int count(struct node*);
void merge(struct node*, struct node*,struct node**);

struct node
{
struct node *link;
int data;
};


void main()
{

struct node *first, *second, *third;
first = second = third = NULL;
clrscr();
add(&first,4);
add(&first,5);
add(&first,567);
add(&first,115);
add(&first,547);
add(&first,567);


printf("\nFirst Linked List is ::\n");
display(first);
printf("No of element in the 1st linked list are::%d",count(first));

add(&second,51);
add(&second,25);
add(&second,-35);
add(&second,45);

printf("\nSecond Linked List is ::\n");
display(second);
printf("No of element in the 2nd linked list are::%d",count(second));

merge(first,second,&third);

printf("\nMerged Linked List is ::\n");
display(third);
printf("No of element in the linked list are::%d",count(third));


getch();
}
    void add(struct node**q, int num)
    {
      struct node *temp=*q,*r;
      r = (struct node*) malloc(sizeof(struct node));
      r->data = num;

      /*if the list is empty or the element is added to the begning*/
      if(*q==NULL || (*q)->data>num)
      {
        *q=r;
        (*q)->link=temp;
      }
      else
      {
        /*traverse the entire linked list to
        search the appropriated position*/
        while(temp!=NULL)
        {
        if(temp->data < num && (temp->link==NULL || temp->link->data>num))
        {
           r->link=temp->link;
           temp->link=r;
           return;
        }
        temp=temp->link;
        }
        r->link=NULL;
        temp->link=r;

      }
    }

    /*Displaying the content in the linked list*/
    void display(struct node *q)
    {
      /*Traverse the entire linked list*/
      while(q!=NULL)
      {
        printf("%d  ",q->data);
        q=q->link;
      }
      printf("\n");

    }


    /*Count the linked list's element*/
    int count(struct node *q)
    {
      int c=0;
      while(q!=NULL)
      {
      q=q->link;
      c++;
      }
      return c;
    }


    /*Merging the both linked list and store in the 3rd linked list*/
    void merge(struct node *p, struct node *q, struct node **s)
    {
      struct node *z;
      z=NULL;

      /*if both the linked list is empty*/
      if(p==NULL && q==NULL)
      return;

      /*Traverse the both linked list till the end of atleast one linked list*/
      while(p!=NULL && q!=NULL)
      {
        /*if node is being added at the starting*/
        if(*s==NULL)
        {
          *s= (struct node *) malloc (sizeof(struct node));
          z=*s;
        }
        else
        {
          z->link= (struct node *)malloc (sizeof(struct node));
          z=z->link;
        }

        if(p->data < q->data)
        {
          z->data=p->data;
          p=p->link;
        }
        else
        {
          if(p->data > q->data)
          {
        z->data=q->data;
        q=q->link;
          }
          else
          {
        if(p->data == q->data)
        {
          z->data = q->data;
          p=p->link;
          q=q->link;
        }
          }
        }
      }



    /*if the end of the first node has not reached*/
    while(p!=NULL)
    {
     z->link=(struct node*) malloc (sizeof(struct node));
     z=z->link;
     z->data = p->data;
     p=p->link;
    }

    /*if the end of the second node has not reached*/
    while(q!=NULL)
    {
     z->link=(struct node*) malloc (sizeof(struct node));
     z=z->link;
     z->data = q->data;
     q=q->link;
    }
    z->link=NULL;
    }