Router #3: 

hostname Router3
enable secret cisco
enable password cisco
!
line vty 0 4
password cisco
login
line console 0
password cisco
login
exit
!
int s0
ip address 10.10.1.2 255.255.255.252
no keepalive
no shutdown
int f0
ip address 172.30.2.1 255.255.255.0
no keepalive
no shutdown
!
router ospf 0
network 10.10.1.2
network 172.30.2.1
exit
!
Exit
!
show run