#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;


long long gcd(long long a, long long b){
	if(b==0) return a;
	return gcd(b, a%b);
}

long long lcm(long long a, long long b){
	if(a<b) swap(a,b);
	if(b==1) return a;
	return a * (b/gcd(a,b));
}


long long extgcd(long long a, long long b, long long &x, long long &y){
	long long d=a;
	if(b!=0){
		d = extgcd(b, a%b, y, x);
		y -= (a/b) * x;
	}else{
		x = 1;
		y = 0;
	}
	return d;
}

vector<pair<long long, long long> > prime_factorization(long long N){
	vector< pair<long long, long long> > ret;
	
	for(long long i=2; i*i<=N; i++){
		long long tmp = 0;
		while(N%i==0){
			tmp++;
			N/=i;
		}
		if(tmp>0){
			ret.push_back( make_pair(i, tmp) );
		}
	}
	if(N!=1){
		ret.push_back( make_pair(N, 1) );
	}
	return ret;
}

int main(){
	long long n;
	cin >> n;

	auto p = prime_factorization(n);
	if(p[0].first == 2){
		if(n%4 == 0 && n%3 != 0){
			cout << 4 << endl;
		}else{
			cout << p[1].first << endl;
		}
	}else{
		cout << p[0].first << endl;
	}


	return 0;
}