Codeforces Round #648 (Div. 2) problem number C.

I am getting TLE in test case 8. This TLE is for log function that I have used in my code. The first number of test case:8 is "576460752303423487". The two base log of "576460752303423487" should be 58 but I am getting 59 that is why I am getting TLE.

long long x, xx; x=log2(n); xx=(ll)pow(2, x);

In this case xx is greater than n, but why? for this reason I am getting TLE. What should I do in this case?

My problem is here 1362C - Johnny and Another Rating Drop My submission is also here 82543228