#include <iostream>

using lint = long long;

void solve() {
    lint n;
    std::cin >> n;

    lint ans = n;
    for (lint p = 2; p * p <= n; ++p) {
        if (n % p != 0) continue;
        if (p > 2) ans = std::min(ans, p);
        if (n / p > 2) ans = std::min(ans, n / p);
    }

    std::cout << ans << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}