If you're going to attempt the following task, you can IP the connections between routers however you like. I did 192.168.xy.z/24 where x is the lower router number, y is the higher, and z is the router number. So the link between R1 and R2 is 192.168.12.z/24. That being said here are the conditions of the task.
1. Area 13 MUST be an NSSA area.
2. Each router can only have a single OSPF process.
3. You may not add any additional interfaces.
4. Only loopback 0 may be advertised into OSPF using network statement, and it may only have the IP of "192.168.z.z/32" where z is the router number. All other loopbacks must be redistributed into OSPF.
5. No static routes are allowed in this lab.
That being said here's the task.
Both R3 and R4 are redistributing a number of Loopbacks into the network. R3 is an NSSA router, configure R3 to advertise Loopbacks 6, 7, 12, and 13 as a single summary. This summary must been seen throughout the OSPF domain, but should not hinder full reachability. When this task is completed all loopbacks should be reachable from all routers.