Can anyone please help me debug my code for the problem CNTPRIME.

I literally tried everything in my arsenal from changing vectors into arrays , using fast I/O , etc.. I tried to compare my solution against accepted solutions from the internet by checking the outputs against random inputs but the effort went in vain as it only shows WA for sufficiently large tests which I could not use to infer anything :(

Please take some time to look into my code and enlighten me. Thanking in anticipation :)