#include <iostream>
#include <cstdio>

using namespace std;

int main() {
	long long n;

	cin >> n;

	long long ans = n;
	if (n % 2 == 0 && n != 4) {
		ans /= 2;
	}

	for (long long i = 3; i * i <= 2 * n; i++) {
		if (n % i == 0) {
			ans = min(ans, i);
			break;
		}
	}

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