#include <algorithm>
#include <iostream>

using namespace std;

int main(int argc, const char *argv[])
{
	uint64_t N;
	cin >> N;
	uint64_t ans					  = N;
	if (N % 2 == 0 && N / 2 != 2) ans = N / 2;
	for (uint64_t i = 3; i * i <= N; i++) {
		if (N % i == 0) {
			ans = i;
			break;
		}
	}
	cout << ans << endl;
	return 0;
}