graph StringGraph {
 0 -- 2 [arrowtail=inv,arrowhead=normal];
 0 -- 16 [arrowtail=inv,arrowhead=normal];
 0 -- 17 [arrowtail=inv,arrowhead=normal];
 2 -- 16 [arrowtail=inv,arrowhead=normal];
 2 -- 17 [arrowtail=inv,arrowhead=normal];
 4 -- 14 [arrowtail=inv,arrowhead=normal];
 4 -- 18 [arrowtail=inv,arrowhead=normal];
 7 -- 9 [arrowtail=inv,arrowhead=normal];
 7 -- 3 [arrowtail=inv,arrowhead=normal];
 9 -- 3 [arrowtail=inv,arrowhead=normal];
 13 -- 9 [arrowtail=inv,arrowhead=normal];
 13 -- 3 [arrowtail=inv,arrowhead=normal];
 13 -- 7 [arrowtail=inv,arrowhead=normal];
 14 -- 18 [arrowtail=inv,arrowhead=normal];
 14 -- 13 [arrowtail=inv,arrowhead=normal];
 16 -- 17 [arrowtail=inv,arrowhead=normal];
 16 -- 4 [arrowtail=inv,arrowhead=normal];
 17 -- 14 [arrowtail=inv,arrowhead=normal];
 17 -- 18 [arrowtail=inv,arrowhead=normal];
 17 -- 4 [arrowtail=inv,arrowhead=normal];
 18 -- 13 [arrowtail=inv,arrowhead=normal];
 18 -- 7 [arrowtail=inv,arrowhead=normal];
}
