#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)s; i < (int)e; i++)
#define all(a) (a).begin(), (a).end()

vector<ll> enum_divisors(ll n) {
    vector<ll> res;
    for (ll i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            res.push_back(i);
            if (n / i != i) res.push_back(n / i);
        }
    }
    
    sort(res.begin(), res.end());
    return res;
}

int main() {
    cin.tie(nullptr);
    
    ll N;
    cin >> N;
    
    vector<ll> divs = enum_divisors(N);
    
    int i = 0;
    while (true) {
        if (divs[i] >= 3) {
            cout << divs[i] << '\n';
            return 0;
        }
        i++;
    }
}