#include <iostream>
#include <cmath>

#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define ll long long

using namespace std;

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

	ll t = N;
	if(N >= 10000) t = sqrt(static_cast<ll>(N));

	int ans = 0;
	rep(i,3,t) {
		if(!(N%i)) {
			ans = i;
			break;
		}
	}

	if(!ans) {
		if(!(N%2) && N/2 > 2) cout << N/2 << endl;
		else cout << N << endl;
	}
	else cout << ans << endl;

	return 0;
}