Failing test case-0
the problem is size of array
to calculate 6000th prime size of array should be atleast 10^7
to make this array we have to declare it globally otherwise runtime error occur
also make bool array as we are storing 0 and 1 only
i have done some other changes also you can see them in modified Code
Modified Code
if you have more doubts regarding this feel free to ask
i hope this helps
if yes hit a like 
: and don’t forgot to mark doubt as resolved 
I hope I’ve cleared your doubt. I ask you to please rate your experience here
Your feedback is very important. It helps us improve our platform and hence provide you
the learning experience you deserve.
On the off chance, you still have some questions or not find the answers satisfactory, you may reopen
the doubt.