OSPF neighbor never comes up — on the CLI

R1 and R2 should be OSPF neighbors on the link between them, but on R2 the neighbor table is empty and the two LANs can’t reach each other. Diagnose R2 with the show commands and bring the adjacency to FULL — there’s more than one valid fix. Type real Cisco IOS commands — abbreviations and Tab-completion work — to find the fault and fix it.