graph LR
A --> B
B --> C
A --> C
B --> D
D --> C
---
+---+     +---+     +---+
|   |     |   |     |   |
| A |---->| B |--+->| D |
|   |     |   |  |  |   |
+---+     +---+  |  +---+
  |         |    |       
  |         |    |       
  |         +----+       
  |         |            
  |         v            
  |       +---+          
  |       |   |          
  +------>| C |          
          |   |          
          +---+          
