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

bool isPrime(long long int n){
	long long int sq = sqrt(n);
	if(n == 1)return false;
	if(n == 2)return true;
	if(n % 2 == 0)return false;
	for(long long int i=3;i<=sq;i+=2){
		if(n % i == 0)return false;
	}
	return true;
}

int main() {
	long long int n;
	
	cin >> n;
	if(n % 2 == 0 & n % 4 != 0)n /= 2;
	if(isPrime(n)){
			cout << n << endl;
	}else{
		for(long long int i=3; i<=n; ++i){
			if(n % i == 0){
				cout << i << endl;
				break;
			}
		}
	}

	return 0;
}