public boolean isFull(int i, int j)		// is site (row i, column j) full?
	{
		if (i<1 || i>N || j<1 || j>N)
		{
			throw new java.lang.IndexOutOfBoundsException();
		}

		return isOpen(i, j) && uf_real.connected(N * (i - 1) + j - 1, N * N);

	}