import java.util.*;

class TreeBuilder {
  Stack s = new Stack();

  TreeBuilder() {
    s.push(null);
  }

  public void addByNode(Node n) {
    s.push((Node) n.clone());
  }

  public Node getTop() {
    return (Node) s.peek();
  }

  public void addNodeByType(Object t) {
    Node n = new Node(t);
    Node temp = null;
    boolean second = false;
    int i = 0;
    try {i = ((Integer) t).intValue();}
    catch (ClassCastException e) {i = TParser.ERROR;}
    switch (i) {
    case TParser.PLUS:
    case TParser.MINUS:
    case TParser.MULT:
    case TParser.DIV:
    case TParser.POW:
    case TParser.MIN:
    case TParser.MAX:
    case TParser.DERIV:
      temp = (Node) s.pop();
      second = true;
    case TParser.NEG:
    case TParser.ABS:
    case TParser.SQRT:
    case TParser.SIN:
    case TParser.COS:
    case TParser.TAN:
    case TParser.SEC:
    case TParser.CSC:
    case TParser.COT:
    case TParser.LN:
    case TParser.LOG:
    case TParser.EXP:
    case TParser.ASIN:
    case TParser.ACOS:
    case TParser.ATAN:
    case TParser.ASEC:
    case TParser.INT:
    case TParser.DBL:
    case TParser.FACT:
      n.addChild((Node) s.pop());
    default:
      break;
    }
    if (second) n.addChild(temp);
    second = false;
    s.push(n);
  }

}