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

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

