public class BinTreeNode<E> {
    public E elem;
    public BinTreeNode<E> left, right;
    public BinTreeNode(E elem,	BinTreeNode<E> left,
				BinTreeNode<E> right) {
        this.elem = elem;
        this.left = left;
        this.right = right;
    }
    public String toString() {
        return this.elem.toString() + (this.left == null ? "" : " L") + (this.right == null ? "" : " R");
    }
}