Thank you very much indeed for your help… At least I found the issue. From the array have to delete the first element, not the last. I changed the pop() method, and now I pass the test
Thanks.
P.s: Once I pass a test I always go to see other solutions on the forum to check different solutions and take some idea how to resolve problems on other way…
The solution of guide is very difficult. I tried to understood the logic, but at least I gave up…