import java.util.Scanner;

public class Solution {

public static String getSmallestAndLargest(String s, int k) {
    String smallest = "";
    String largest = "";
    java.util.List<String> total = new java.util.ArrayList();

    // 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=0;i<=s.length()-1;i++)
    {
        try{
        String sort = s.substring(i, k+i);
        total.add(sort); 
        }
        catch(Exception e)
        {
            break;
        }
    }
    java.util.Collections.sort(total);
    smallest = total.get(0);
    largest = total.get(total.size()-1);

    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));
}

}