#include <iostream>
#include <cstdio>

using namespace std;

int main() {
	long long n;

	cin >> n;
	long long ans = n;
	long long limit = 1e7;
	for (long long i = 3; i <= limit; i++) {
		if (n % i == 0) {
			ans = i;
			break;
		}
	}

	cout << ans << endl;
	return 0;
}