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