I get it, as I was very confused at first too, as I understood that you had to:

1. first remove the leftmost character
2. then remove every letters "a" that are followed by the letter "b"

I finally understood that the description was confusing (to me) in its wording.

May I suggest this modification ?:

- start by removing all letters 'a', then all letters 'b', then all letters 'c', etc...

- always start with the leftmost character.

It might just be me, but for me first means before anything else (even what I just said before), and the followed by without a verb could mean both that is followed by and then.
But again, that might just be me, as I'm not an English speaker.

pit here means like a trap, or an unexpected condition

can you please describe "pit".

a b c d e f g ....

could be that u used int() in the process ? Because then it does not give you the exact result in the end if you used it several times in your code

shut up mommy

I passed 3 of 8 tests, but other not passed tests results are like myResult - 1 = Test result. WTF???

The task solve without sieve of Eratosthenes
Is it right?

expected:<[3[37, 34]7]> but was:<[3[07, 31]7]> what a f***????
My own tests are passed and passed successfully. Check tests before deploying kata...

In general, I'd agree with you that it's not terribly difficult, but there is a pit that many fall into.

'alr approved some time ago'

I think that kata is too easy for 5 kyu but it's funny

Nice kata. Sure it's too hard for a 7 kyu because a basic classic loop won't work and some optimization is required, but the sensei is not responsible for that. I had to use a regex feature I never used before to solve it (Python). This kata eventually taught me something very useful. Thanks!

first remove all letter 'a', followed by letter 'b', then 'c', etc...

The letters are removed alphabetically and starting from the left.

in test with k=8 output must be 'rdr'? I don't think so. 1) delete from left 5 a => brcdbr, 2) delete from left 2 b => rcdr, 3) delete from left 1 r => cdr. Not rdr, who knows why rdr?