I got TLE on testcase 3 and I know test3 is testing near 10^18. Im using the square root method to solve the problem and the loop starts with the value from the square root function. However for numbers that are close to 10^18, the loop will run approximately 30,000 times and I know this is the problem with my solution. Can anyone tell me some ways that I could use to make the solution faster?

btw I'm doing this in C++.

Thanks :)