#include <iostream>
#include <cmath>

typedef long long dlong;


int main(int argc, char const* argv[]) {
    dlong n;
    std::cin >> n;

    if (n % 4 == 0 && n % 3 != 0) {
        std::cout << 4 << std::endl;
        return 0;
    }

    dlong ans  = n;
    dlong imax = sqrt(n);
    for (dlong i = 3; i <= imax; i+=2) {
        if (n % i == 0) {
            ans = i;
            break;
        }
    }
    if (ans == n && n % 2 == 0) ans /= 2;

    std::cout << ans << std::endl;
    return 0;
}