#include <string>
#include <iostream>
#include <cmath>
using namespace std;

typedef long long int ll;

int main()
{
	ll n;
	cin >> n;

	if (n == 3) {
		cout << 3 << endl;
		return 0;
	}

	if (n == 4) {
		cout << 4 << endl;
		return 0;
	}

	if (n == 5) {
		cout << 5 << endl;
		return 0;
	}

	if (n == 6) {
		cout << 6 << endl;
		return 0;
	}

	if (n == 7) {
		cout << 7 << endl;
		return 0;
	}

	if (n == 8) {
		cout << 8 << endl;
		return 0;
	}

	if (n % 2 == 0) n /= 2;

	for (ll i = 2; (ll)(i*i) <= n; i++) {
		if ((n%i) == 0) {
			cout << i << endl;
			return 0;
		}
	}


	cout << n << endl;

	return 0;
}