#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>

//#include<bits/stdc++.h>



using namespace std;




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

	return 0;
}