#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#include <string>
#include <algorithm>
#include <iomanip>
using namespace std;
typedef long long ll;

ll f(ll n) {
	ll ret = n;
	for(ll i = 2; i * i <= n; i++) {
		if(n % i == 0) {
			if(i != 2) {
				ret = min(ret, i);
			}
			if(n / i != 2) {
				ret = min(ret, n / i);
			}
		}
	}
	return ret;
}

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	ll N;
	cin >> N;
	cout << f(N) << endl;
}