I was playing blitz yesterday and got a position, where I delivered mate in 3 moves. Afterwards I ran the game through Fritz and Fritz said that my opponent didn’t chose the best continuation ( I knew that) , anyway there was a mate in 8  ( I didn’t know that). I found it interesting and made a calculation training exercise out of it.  I almost solved it, it was a wrong order of moves on the end. I offer you to try it, the answer is in the first comment. White to move: