it doesn't work on dart.
i tried my solution on pc and dart pad - all works perfectly.
but here it fail tests every time.
maybe it is something to o with dart vesions(here is 2.1 and dart is already 2.7), i dunno.

and it's not 6 kyu kata. it's atleast 5.

you are a man of Italian culture.
Cool solution.

this is fun solution, but pretty heavy to read.
you clearly a man.