#include<iostream>

using namespace std;

int main(){

	long long N;

	cin>>N;

	for(long long i=3;i*i<=N;i++){
		if(N%i==0){
			cout<<i<<endl;
			return 0;
		}
	}

	if(N%2==0&&N!=4) cout<<N/2<<endl;
	else cout<<N<<endl;
}