https://www.e-olymp.com/uk/problems/1642

main.cpp

#include <bits/stdc++.h>
using namespace std;
using ull = unsigned long long;

ifstream in("input.txt");
ofstream out("output.txt");

int main() {
	ull n;
	in >> n;

	if (n == 4) {
		out << "NO" << endl;
		return 0;
	}

	ull k = n;
	for (ull i = 2; i * i <= n; ++i) {
		if (n % i == 0) {
			ull b = n / i;

			if (k % i == 0) {
				k /= i;
			}
			if (k % b == 0) {
				k /= b;
			}
		}
	}
	out << ((k == 1) ? "YES" : "NO") << endl;

	return 0;
}