Arb AB_CrNod(void *ch, Arb s, Arb d, Arb p, int dir)
{
	Arb r=(Arb) malloc(sizeof(struct arb));
	r->key=ch;
	r->st=s;
	r->dr=d;
	r->pred=p;
	if (p)
		switch(dir)
		{
		case -1: p->st=r;break;
		case 1: p->dr=r;break;
		case 0: ;
		}
	return r;
}

Arb AB_CrArb(Arb r, Arb s, Arb d)
{
	assert(r);
	AB_SetSS(r,s);
	AB_SetSD(r,d);
	return r;
}

Arb AB_Copy(Arb a)
{
	if (AB_Empty(a)) return NULL;
	Arb b=AB_CrNod(AB_GetKey(a),NULL,NULL,NULL,0);	
	Arb s=AB_Copy(AB_GetSS(a)); 	
	Arb d=AB_Copy(AB_GetSD(a));			
	return AB_CrArb(b,s,d);
}