notes/school/di-ma/20181121_1-euler.dot

graph g {
    node [ shape="circle" ];
    {
        rank="same";
        1;
        3;
        5;
        6;
    }

    2 -- 1 -- 4;
    2 -- 3 -- 4;
    2 -- 5 -- 4;
    2 -- 6 -- 4;
}