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

