Yesterday, when I was writing virtual contest in GYM, I found some interesting feature. From status I could find number of tests, I guess it works for any problem. However, I have not tested it for official round, but at all it's worth for a new blog. In the status-filter bar, you maybe have seen a section "test", but you probably dont know the magic, which can be done with it.

By changing sign to $$$\geq$$$(is greater than or equal to) and giving number to this empty space you can find number of test. If you found that maximal $$$x$$$, that all submissions are accepted and no submissions at $$$x + 1$$$, $$$x$$$ is the number of test. You may ask, why binary search is written in the title. It's the most optimal and the fastest way to find this number, less than 10 steps)

P.S. Sorry for my poor English