#include using namespace std; constexpr int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); } constexpr int totient(int x, int i) { return i == 0 ? 0 : (gcd(x, i) == 1) + totient(x, i - 1); } constexpr int totient(int x) { return totient(x, x - 1); } int main() { constexpr auto x = totient(NUMBER); cout << x << endl; }