import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        int k = sc.nextInt();

        String small = s.substring(0, k);
        String lar = s.substring(0, k);

        for (int i = 0; i <= s.length() - k; i++) {
            String sub = s.substring(i, i + k);

            if (sub.compareTo(small) < 0) {
                small = sub;
            }

            if (sub.compareTo(lar) > 0) {
                lar = sub;
            }
        }

        System.out.println(small);
        System.out.println(lar);
    }
}