package HackerRank;

import java.util.Scanner;

public class ThirtySeven {

    public static String getSmallestAndLargest(String s, int k) {
        String smallest = s.substring(0, k);
        String largest = s.substring(0, k);

        
        // Complete the function
        // 'smallest' must be the lexicographically smallest substring of length 'k'
        // 'largest' must be the lexicographically largest substring of length 'k'
        for (int i = 1; i <= s.length() - k; i++) {
    String substring = s.substring(i, i + k);
    if (substring.compareTo(smallest) < 0) {
        smallest = substring;
    }
    if (substring.compareTo(largest) > 0) {
        largest = substring;
    }
}
        return smallest + "\n" + largest;
    }


    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String s = scan.next();
        int k = scan.nextInt();
        scan.close();
      
        System.out.println(getSmallestAndLargest(s, k));
    }
}
}