transition:    
p1-a-p2;
p2-c-p1;
p2-d-p9;
p1-a-p3;
p3-b-p4;
p4-a-p5;
p5-b-p4;
p1-a-p6;
p6-d-p3;
p6-c-p1;
p1-a-p7;
p7-b-p10;
p7-a-p8;
p8-b-p9;
p9-d-p10;
p10-a-p5;
initial:
p1;
final:
p1;
p5.