node 1 node 1-1 node 1-2 node 1-3 node 1-3-1 node 1-3-2 node 1-3-3 node 2 node 2-1 node 2-2 node 2-3 node 3 node 3-1 node 3-2 node 3-3 node 3-3-1 node 3-3-2 node 3-3-3