I met this issue as well. More interestingly, if you calculate the difference between your answer and the correct (presumably?) answer, they always differ by a number that has a high power in 2 when prime factorized, like 1736704 (2^15 * 53) or 16384 in the case of IMMUNOELECTROPHORETICALLY, which is 2^14.

Since the clan has already been grouped, if you partitioned it, each of them will be unique

Please, see the answer below...

@pilgrim_ manual notification (see above)

Yep, this should be mentioned in description.

For these two, we have the following events:

• before 2019-04-01 there were no visitors,
• at 2019-04-01 00:00:00 first one arrived, we now have one visit in progress,
• at 2019-04-03 00:00:00 second one arrived, we now have two visits in progress,
• at 2019-04-10 00:00:00 the first one is gone, so we are down to only one visitor,
• finally, at 2019-04-13 00:00:00 no one is left.

The maximum number of simultaneous visitors is: ?

There were that many visitors visiting between: ? and: ?

The earliest time when there were ? concurrent visitors is at the start of that timespan.

Not an issue. Use proper division.