import java.util.*;

public class Main {

	protected static ArrayDeque<String> pile;

	public static void main(String[] args) {
		Main.pile = new ArrayDeque(args.length);

		for (int i=0; i<args.length; i++){
			Main.pile.push(args[i]);
		}

		Noeud noeudDeb;
		String debutArbre = Main.pile.pop();
		if (debutArbre.equals("+")||debutArbre.equals("-")||debutArbre.equals("x")||debutArbre.equals("/")){
			noeudDeb = new NoeudOperation(debutArbre);
		}
		else{
			noeudDeb = new NoeudChiffre(debutArbre);
		}
		noeudDeb.afficherNoeud();
	}
}