endgame study, very tough

                     white to play:

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After 1. Qf3+   1....?
(see https://www.shredderchess.com/online-chess/online-databases/endgame-database.html)
........
If. 1. Qf3+   Kc5 (1...Kc4 is actually correct in order to draw)
2. Kg4  Kb4
3. Qf5  Qg7    we reach this position: