#include"bits/stdc++.h"
//#include<bits/stdc++.h>
using namespace std;
#define print(x) cout<<x<<endl;
#define rep(i,a,b) for(int i=a;i<b;i++)
typedef long long ll;
const int mod = 1000003;

int main() {
	ll n;
	cin >> n;
	for (int i = 3;i<=sqrt(n)+10;i++) {
		if (n%i == 0) { print(i); return 0; }
	}
	n = n % 2 == 0 ? n / 2 : n;
	print(n);
	return 0;
}