50 maybe. But you should start over at 1-4. The anime skipped a few chapters and the last episodes try a lot to connect to the manga (the anime is currently ahead of the manga/doing its own thing, since 1 death has not even happened yet in the manga.
What happened exactly in episode 19? Then I can give you a chapter.
But the manga is just more detailed in the beginning, the anime didn't show a lot of stuff so starting from the bottom may help but you'll already know the gist of what's happening.