#include <iostream>
using namespace std;

int main() {
	// your code goes here
	long long int n,ans=-1;
	std::cin>>n;
	if((n%2==0)&&(n/2!=2)){
		ans=n/2;
	}
	
	for(long long int i=3;i*i<=n;i++){
		if(n%i==0){
			ans=i;
			break;
		}
	}
	if(ans==-1)ans=n;
	std::cout<<ans<<"\n";
}