JD *zxxsh(JD *bt)
{  JD *p,*pr,*s[M],*t;
   int i=0;
   t=(JD *)malloc(sizeof(JD));
   t->lt=0;
   t->rt=1;
   t->rc=t;
   if(bt==NULL)
      t->lc=t;
   else
   {  t->lc=bt;
      pr=t;
      p=bt;
      do
      {   while(p!=NULL)
	  {   s[i++]=p;
	      p=p->lc;
	  }
	  if(i>0)
	  {   p=s[--i];
	      printf("%c  ",p->data);
	      if(p->lc==NULL)
	      {   p->lt=1;
		  p->lc=pr;
	      }
	      if(pr->rc==NULL)
	      {   pr->rt=1;
		  pr->rc=p;
	      }
	      pr=p;
	      p=p->rc;
	  }
      }while(i>0||p!=NULL);
      pr->rc=t;
      pr->rt=1;
      t->rc=pr;
   }
   return(t);
}