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

