digraph G {
0 -> 1 [label="0 "];
0 -> 2 [label="1 "];
1 -> 1 [label="0 1 "];
2 -> 1 [label="1 "];
2 -> 3 [label="0 "];
3 -> 3 [label="0 1 "];
2[peripheries=2];
3[peripheries=2];
0[shape=diamond];
}
z