Graph Nodes:
X1;X2;X3;X4;X5;X6;X7;X8;X9;X10;X11;X12;X13

Graph Edges:
1. X1 --> X10
2. X1 --> X13
3. X1 --> X2
4. X10 --> X11
5. X11 --> X12
6. X11 --> X13
7. X2 --> X13
8. X3 --> X11
9. X3 --> X7
10. X4 --> X5
11. X4 --> X7
12. X5 --> X10
13. X5 --> X11
14. X5 --> X8
15. X6 --> X10
16. X6 --> X8
17. X7 --> X12
18. X8 --> X11
19. X9 --> X10
20. X9 --> X11

