#include<stdio.h>

typedef struct node {
    int data;
    struct node *leftlink;
    struct node *rightlink;
}node;

node *start=NULL;
node *tail=NULL;

void add_begin(node *);
main()
{
   
 .......
 .......

add_begin(start);

 .......
 .......
}

void add_begin(node *temp)
{
   node *new_node=NULL;
   int idata;
   printf("enter the data part value: ");  
   scanf("%d",&idata);

   if(start==NULL && tail==NULL )
   {
      new_node=(node *)malloc(sizeof(node));
      new_node->data=idata;
      new_node->leftlink=NULL;
      new_node->rightlink=NULL;
      start=new_node;
      tail=new_node;
   }
   else
   {
      new_node=(node *)malloc(sizeof(node));
      new_node->data=idata;
      temp->leftlink=new_node;
      new_node->rightlink=temp;
      new_node->leftlink=NULL;
      start=newnode;
   }
}