Pay attention to this: "Oleg stops drinking as soon as there is no cocktail on the current height. But in case barman pours the liqueur exactly at this moment Oleg continues drinking".

So, for the test
3
1 a 30
20 Oleg 20
31 a 30
correct answer is:
20-30 a
and not is
20-30 a
31-61 a

This helped me to pass 2nd test.

Yes you can, in practice it will be max value of type used for storing straw height.

I also WA#2.