We have several WiFi routers placed at various (x,y) coordinates in a given 2D plane. 

All the routers have a signal range of 10 units and each router has a unique name. 

If a router receives a message, it will broadcast it to all reachable routers within its range and shut itself down almost instantly.

For simplicity, assume you are already provided with an implementation of the distance(Router a, Router b) method.

Given a list of routers, a source router, and a target router, return true if the source router can broadcast a message to the target router.