[Event "?"]  [Site "?"]  [Date "2017.07.26"]  [Round "?"]  [White "Study #21"]  [Black "?"]  [Result "1-0"]  [SetUp "1"]  [FEN "8/6Pb/7P/8/8/8/1K5P/4k3 w - - 0 1"]  [PlyCount "15"]   1. Kc3 {[pgndiagram] The first move is quite obvious. White heads for f7} Kf2 {  Black in response goes to h5} 2. Kd4 Kf3 3. Ke5 Kg4 4. Kf6 Kh5 {[pgndiagram]  The critical position has arisen. White can't continue with his planned king  advance as Black would take on h6 and draw. White has to be more crafty than  that} 5. g8=Q $1 {[pgndiagram] The only move to win}   (5. Kf7 Kxh6 6. g8=Q Bxg8+  7. Kxg8 {[pgndiagram] Leads to a draw}) 5... Bxg8 6. Kg7 Kg5 {But now it seems  that White still doesn't have anything. But the position is actually a mutual  zugzwang} 7. h3 $1 {[pgndiagram] The right way}   (7. h4+ Kh5 {And White has to  move his king, after which h6 falls and it is a draw}   (7... Kxh4 {Obviously not  } 8. Kxg8)) 7... Kh5 8. h4 {[pgndiagram] And Black is in zugzwang. A nice  finish} 1-0