Simple Routing question with Loopback ip addresses

RouterOS Forwarding Protocols
1

Hi
How to enable communications between hotspot Access Points in the given image scenario. I want to ping A4 loopback interface ip on A1 access point, from A1 loopback interface on A4 access point?

  1. Answere with static routes thx.
  2. Answer with OSPF routing. thx

thx
loopback.PNG