digraph test { 
n0[ color=green , fontcolor=red ];
n1;
n2;
n3[ fontcolor=red ];
n4[ fontcolor=red ];
n0 -> n1[ label= "A"];
n0 -> n2[ label= "B"];
n1 -> n3[ label= "X"];
n2 -> n4[ label= "Y"];
n3 -> n1[ label= "A"];
n3 -> n2[ label= "B"];
n4 -> n1[ label= "A"];
n4 -> n2[ label= "B"];
}
