digraph foo {
rankdir = LR;
s;
1;
2;
3;
4;
5;
6;
t;
s->1 [label="0,1"];
s->3 [label="0,1"];
1->2 [label="10,1"];
1->4 [label="15,1"];
2->4 [label="5,1"];
4->6 [label="0,1"];
6->t [label="0,1"];
}