private STNode<Key, Value> rotateLeft(STNode<Key, Value> x)
	{
		STNode<Key, Value> t = x.right;
		x.right = t.left;
		t.left = x;

		x.N = size(x);
		t.N = size(t);

		x.h = height(x);
		t.h = height(t);

		return t;
	}