digraph G {
            0 -> 7;
            1 -> 2;
            2 -> 3;
            3 -> 1;
            4 -> 0;
            4 -> 9;
            5 -> 4;
            6 -> 4;
            6 -> 8;
            7 -> 11;
            8 -> 5;
            9 -> 6;
            9 -> 10;
            10 -> 0;
            10 -> 1;
            11 -> 7;
            11 -> 12;
            12 -> 6;
        }