digraph g {
        __start0 [label="" shape="none"];
        __start0 -> q1;

    	q1 [shape="circle" label="q1"];
    	q2 [shape="circle" label="q2"];
    	q3 [shape="circle" label="q3"];
	q4 [shape="circle" label="q4"];

    	q1 -> q2 [label="a / 0"];
    	q1 -> q3 [label="b / 0"];
    	q2 -> q1 [label="a / 1"];
    	q2 -> q4 [label="b / 0"];
    	q3 -> q4 [label="a / 0"];
    	q3 -> q1 [label="b / 1"];
	q4 -> q3 [label="a / 0"];
    	q4 -> q2 [label="b / 0"];
    }