typedef struct node
{  int data;
   struct node *lchild,*rchild;
}JD;
JD *insertbst(JD *r,int x)
{  JD *p,*q,*s;
   s=(JD *)malloc(sizeof(JD));
   s->data=x;  s->lchild=s->rchild=NULL;
   q=NULL;
   if(r==NULL) {  r=s; return(r);}
   p=r;
   while(p!=NULL)
   {  q=p;
      if(x<p->data)
         p=p->lchild;
      else
         p=p->rchild;
   }
   if(x<q->data)
      q->lchild=s;
   else
      q->rchild=s;
   return(r);
}