#include<iostream>
#include<cassert>
using namespace std;
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	long N;cin>>N;
	for(long p=3;p*p<=N;p++)if(N%p==0)
	{
		cout<<p<<endl;
		return 0;
	}
	if(N%2==0&&N/2>=3)cout<<N/2<<endl;
	else cout<<N<<endl;
}