It is black to move. Is this a draw or loss for black?
How should black proceed?
Yes, general principles seem to work here. 1...Ke6 2. Kb6 Kd7 3. Kb7 Nf5 4. Be5 Ne7 and now 5. a5 Nc6 6. a6 Nd8+ 7 Kb6 Nc6! and now White cannot get the pawn to a7 let alone a8.
I'm sure I could handle this at the board without undue time trouble, since the idea is to keep White's K from b7 and the N on the board.
1...Ke8!!!, 2. Bf6?! Kd7!, 3. Bxh4 Kc7!, 4. Ka6 Kb8, 5. Bg3+ Ka8! (Draw because of a wrong rook pawn —- White cannot win)
1...Ke8!, 2. Kb6 Kd7, 3. a5 Nf5, 4. a6 Ne7!!, 5. Bf6 Nc6!, 6. Kb7 Na5+, 7. Kc5 Nc6, 8. Kb6 Kd6! = Draw!!!
There are 4 drawing moves. Three of them were easy for me to spot, but the fourth one surprised me when I saw it in the Nalimov. I hate knights.
1...Ke8 2.Kb6 Kd7 3.Kb7 Nf5 4.Be5 Ne3 5.a5 Nc4 6.a6 Na5+ 7.Kb6 Nc6 8.Bh2 Ne7 9.Bg3 Nc6 10.Bf4 Ne7 11.Kc5 Nc6 12.Bg3 Na7 13.Bh2 Nc6 14.Bf4 Na7
it's a draw