#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

vector<ll> findDivisor(ll n) {
	vector<ll> divisor;
	for (ll i = 1; i * i <= n; i++) {
		if (n % i == 0) {
			divisor.push_back(i);
			if (i * i != n) divisor.push_back(n / i);
		}
	}
	return divisor;
}

int main() {
	ll n;
	cin >> n;
	
	vector<ll> div = findDivisor(n);
	
	ll ans = 1ll<<60;
	REP(i, div.size()) if (div[i] >= 3) {
		chmin(ans, div[i]);
	}
	cout << ans << endl;
	return 0;
}