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

bool isPrime(long long int n)
{
	for (int i = 2; i*i <= n; i++) {
		if (n%i == 0) return false;
	}
	return true;
}

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

	if (isPrime(n)) {
		cout << n << endl;
	}

	for (int i = 3; i*i <= n; i++) {
		if (n%i == 0) {
			cout << i << endl;
			break;
		}
	}

	return 0;
}