In today's contest during submission of my solution of B question then I got runtime error again and again and not able to understand the reason for it because I don't get any error in my VSCode IDE. I am putting a link of my solution and also commented that line which gives an error so, please tell me why it is giving runtime error? Thanks for your help.

Question link: https://mirror.codeforces.com/contest/1350/problem/B Solution link: https://mirror.codeforces.com/contest/1350/submission/79905645