link — http://codeforces.net/contest/791/problem/B

I used the fact that each in each connected component there should be an edge between each pair of vertices. Hence the number of edges given should be equal to — summation x*(x-1)/2 for each connected component, where x = size of the connected component.

I used int and got a WA and when I replaced it with long long it got Accepted. Now my question is if the answer has to be "YES

" then sum should be <= 150000 (since that is the range of M in the question) so int should suffice then why did I get a WA?

WA link — http://codeforces.net/contest/791/submission/25610369 AC link — http://codeforces.net/contest/791/submission/25625604

Thanks in advance!