digraph foo
{
        rankdir=LR;
        s;
        t;
        a;
        b;
        c;
        d;
        s->a->b->d->t [label="1/1"];
        a->c->d [label="1/5"];
        d->c->a [label="0/5"];
        d->b->a [label="1/5"];
};