import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class prog {
    public static void main(String[] args) throws java.lang.Exception {
        Scanner scanner = new Scanner(System.in);
        long n = Long.parseLong(scanner.nextLine());
        long initial = n;
        List<Long> divisiors = new ArrayList<Long>();
        for (long i = 2; i <= Math.sqrt(n); i++) {
            if (n % i == 0) {
                if (!divisiors.contains(i)) {
                    divisiors.add(i);
                    n /= i;
                    i = 1;
                }
            }
        }
        if (n == initial) {
            System.out.println(n - 1);
        } else if (!divisiors.contains(n) || n == 1) {
            System.out.println(0);
        } else {
            System.out.println(n);
        }
        scanner.close();
    }
}