P2508 [HAOI2008] Lattice Points on a Circle
Description
Given the circle $(x^2+y^2=r^2)$, determine how many points on its circumference have integer coordinates.
Input Format
A single integer $r$.
Output Format
The number of lattice points.
Explanation/Hint
Constraints: $r\leq 2000 000 000$.
Translated by ChatGPT 5