I've used those thing:
- binary search
- sys.stdin.readline() instead of input
- http://acm.timus.ru/forum/thread.aspx?id=30704&upd=636446663176701082
- checked min/max teacher's dates and didn't below/over them

and still have just 1.514-1.544

What's wrong? What's idea behind that?

same

use sets it's easy with them