Graph Nodes:
X1;X2;X3;X4;X5;X6;X7;X8;X9;X10;X11;X12;X13;X14;X15;X16;X17;X18;X19;X20

Graph Edges:
1. X1 --> X12
2. X2 --> X8
3. X3 --> X8
4. X3 --> X9
5. X4 --> X10
6. X5 --> X11
7. X6 --> X13
8. X12 --> X14
9. X12 --> X15
10. X12 --> X16
11. X12 --> X17
12. X12 --> X18
13. X12 --> X19
14. X12 --> X20
15. X15 --> X7
16. X16 --> X2
17. X17 --> X2
18. X17 --> X3
19. X18 --> X3
20. X18 --> X4
21. X18 --> X5
22. X18 --> X6
23. X19 --> X5
24. X20 --> X6
25. X20 --> X14
