Hardest Chess Puzzle Ever

Chess is a game with 99% tactics, which means you need to train your chess tactics, NOT being lucky to win. One of the best ways to train your tactics is through chess puzzles, on chess.com usually, it starts from the very easy puzzle to the hard level. What is the hardest chess puzzle you ever had? maybe in the chess.com puzzles or on other sites or in real life? here I have some of those HARD puzzles. Ready? 1... 2... 3...

here number 1, maybe it wasn't that hard isn't it? but can you solved it? white have a crazy sacrifices but there is some more that is harder. 

Number 2, this endgame is hard and full of tricks

So what do you think about this no hint? hard? yup the knight is great,

This is the impossible, looks like this 5 same colored-square bishop is impossible to end. but, give it a try and you will see 

So, the answer is possible, but we know that it will never (or 0,1%) happened in a real game.

Now look at this. try to solve it

Great queen sac and the passe pawn wins for the puzzle above.

And this is the final one, a zugzwang

Solve it all? which one is the hardest? tell me in the comments.