notes/school/di-ma/20181113_2-adjlist.dot

graph {
    {
        rank=same;
        1; 3;
    }

    {
        rank=same;
        2; 4;
    }

    {
        rank=same;
        5; 6;
    }
    1 -- 2
    1 -- 3
    1 -- 4
    2 -- 4
    5 -- 6
}