private K key;
private V value;
Tree<K, V> left;
Tree<K, V> right;
private boolean isMax = false;

public K max() throws EmptyTreeException {
		if(right.toString()!=""){
			return right.max();
		}
		else
		        this.isMax = true;
			return this.key;
	}

public String toString() {
  		String result = "";
  		result+=(this.left.toString());
  		result+=this.key;
  		result+="=>";
  		result+=this.value;
  		if(this.isMax != true){
  			result+=" ";
  		}
  		result+=this.right.toString();
  		return result;
  	}