public Node firstAncestor_bad(Node r, Node n, Node m){
		if(r == null) return null;
		if(r == n || r == m) return r;
		Node x = firstAncestor_bad(r.left,n,m);
		Node y = firstAncestor_bad(r.right,n,m);
		if(x == null && y == null)
			return null;
		else if(x == null)
			return y;
		else if(y == null)
			return x;
		else 
			return r;
	}