#include <stdint.h>

/**
 * @brief Calculate the greatest common divisor (GCD)
 *
 * @param a First integer
 * @param b Second integer
 * @return greatest common divisor between a and b
 */
constexpr uint64_t gcd(const uint64_t a, const uint64_t b) noexcept { return a == 0 ? b : gcd(b % a, a); }