i got it.
Thanks! :)

If n is 1, then "This kata is very interesting!"

Take every 2nd char from the string, then the other chars, that are not every 2nd char, and concat them as new String."

Becomes "hskt svr neetn!Ti aai eyitrsig" the lenght is always the same, you only took every 2nd char, and forgot to concatenate the other part.

what does it mean 'Do this n times!' ?
for ["This kata is very interesting!", 1] case, when should i stop ?
my understanding is it shouold stop when rolled to text[-1]...
my answer is 'hskt svr neetn!'
confusing...

Thanks,I thought the second key was length of string.

As strings 1 comes before 2 as a comes before b.

Print the input, it seems in that case it's empty and your code returned 0

All numbers in the list are positive numbers and the list can be empty.

got it ... THANKS!

Print the input values, see why.

read the complete error message to see from where the error is raised, then amend your code. ;) (and don't forget to print stuff to the console if needed at some point).

EDIT : and read the message just below...?

Closing then.