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How many moves until checkmate? (White's turn)

https://syzygy-tables.info/?fen=8/6k1/8/P7/5R1p/7N/r7/6K1_w_-_-_0_1

[Variant "From Position"]
[FEN "8/6k1/8/P7/5R1p/7N/r7/6K1 w - - 0 1"]

  1. Rf5 Kg6 2. Rb5 Ra4 3. Ng5 Kf6 4. Nf3 Ra1+ 5. Kf2 Ra2+ 6. Ke3 Ra4 7. Kd2 Ke6 8. Rh5 Ra2+ 9. Kc1 Ra1+ 10. Kb2 Rb1+ 11. Kxb1 Kd6 12. a6 Ke7 13. Nxh4 Kd6 14. a7 Ke6 15. a8=Q Ke7 16. Rh6 Kf7 17. Kc2 Ke7 18. Qa7+ Kd8 19. Rh8#

So the multi engines rated over 3000 could not solve it.
Nice one...

https://syzygy-tables.info/?fen=8/6k1/8/P7/5R1p/7N/r7/6K1_w_-_-_0_1 [Variant "From Position"] [FEN "8/6k1/8/P7/5R1p/7N/r7/6K1 w - - 0 1"] 1. Rf5 Kg6 2. Rb5 Ra4 3. Ng5 Kf6 4. Nf3 Ra1+ 5. Kf2 Ra2+ 6. Ke3 Ra4 7. Kd2 Ke6 8. Rh5 Ra2+ 9. Kc1 Ra1+ 10. Kb2 Rb1+ 11. Kxb1 Kd6 12. a6 Ke7 13. Nxh4 Kd6 14. a7 Ke6 15. a8=Q Ke7 16. Rh6 Kf7 17. Kc2 Ke7 18. Qa7+ Kd8 19. Rh8# So the multi engines rated over 3000 could not solve it. Nice one...