Ehhh this hackerrank disappointed me) I write such a code, like everything works, tests pass. Send to check all the tests, does not pass 3 pieces, and looking for bugs, found one bug, then fixed and sent again. Then he says that only one test does not pass, 30 minutes left and began to think about what test may not pass.

And then BAM! hackerrank rebooted and all my code disappeared :D and I wrote there in 40 minutes so much code (f*ck) and I started to panic even and began to rewrite by memory (with couple of bugs cause I am human firstly), remained until the end of time ~ 3 minutes, I finished and returned to the state with one error;) and sent the code because I did not have time.