1001kyu: F2G1L2K1L3L1N2N1 is a ko, so L3 actually fails, and the one with atari at F1 first as well, the rest are fine.
caranthir: According to Katago, playing that ko is about 8 points worse than connecting, then after atari, sacrificing the five stones and taking the three with M16. In other words: If they responded otherwise correctly, accepting the ko is the only way they could lose everything. ------ This is also why in this variation, whe should play M16 instead of L17 (althoug in that specific variation, we do end with sente, so it isn't the worst either.). Now enemy should connect at M16. Then K19L17J19. We captured the five stones in a bigger way and only sacrificed one for the time being.
1001kyu: I might be wrong, but playing L18 before K19 also seems possible. At least I don't see a refutation. Here's a few variations:
L18K19L19L18L17K19L18J19K19
And so on, most of them go back to the variation where you play K19 first.
Ivan Detkov: L18 is working. I added quite a significant number of variants, which are starting from your move.
According to Katago, playing that ko is about 8 points worse than connecting, then after atari, sacrificing the five stones and taking the three with M16. In other words: If they responded otherwise correctly, accepting the ko is the only way they could lose everything. ------ This is also why in this variation, whe should play M16 instead of L17 (althoug in that specific variation, we do end with sente, so it isn't the worst either.). Now enemy should connect at M16. Then K19 L17 J19. We captured the five stones in a bigger way and only sacrificed one for the time being.