#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>
#include<limits>

using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;

int main()
{
	ll N;
	cin >> N;

	for (ll i = 3; i <= sqrt(N)+2; i++) {
		if (N % i == 0) {
			cout << i << endl;
			return 0;
		}
	}
	if (N % 2 == 0)
		cout << N / 2 << endl;
	else
		cout << N << endl;
	return 0;
}