void stergpu( nodd *&prim)
 {nodd *q=prim;
  prim=prim->urm;
  prim->prec=0;
  delete q;
  nodd *u=prim;
  while(u->urm) u=u->urm;
  nodd *p=u->prec;
  p->urm=0;
  delete u;
 }