digraph G {
        a [label="A", style="filled", fillcolor="yellow"];
        b [label="B", style="filled", fillcolor="yellow"];
        c [label="C", style="filled", fillcolor="yellow"];
        d [label="D", style="filled", fillcolor="yellow"];
        a->c [label="5"];
        b->b [label="1"];
        c->b [label="3"];
        d->b [label="2"];
        d->c [label="8"];
}