//#include <atcoder/all>
#include <bits/stdc++.h>
#include <cmath>
using namespace std;
//using namespace atcoder;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
using Graph = vector<vector<ll>>;
Graph G;
vll E;
vector<bool> seen;

int main() {
	ll N;
	cin>>N;
	for(ll i=3;i*i<=N;i++){
		if(N%i==0){
			cout<<i<<endl;
			return 0;
		}
	}
	if(N%2==0&&N/2>2)cout<<N/2<<endl;
	else cout<<N<<endl;
}