typedef struct node
{   int  data;
struct  node  *next;
}JD;
JD  *interset(JD *la, JD *lb)
{   JD  *lc, *p, *q, *r;
p=la;
q=lb;
lc=(JD *)malloc(sizeof(JD));
r=lc;
while((p!=NULL) && (q!=NULL))
{   if (p->data > q->data)
        q=q->next;
    else  if (p->data < q->data)
        p=p->next;
    else
    {   r->next=(JD *)malloc(sizeof(JD));
        r=r->next;
        r->data=p->data;
        p=p->next;
        q=q->next;
    }
}
r->next=NULL;
u=lc;
lc=lc->next;
free(u);
return(lc);
}