import java.io.*;
import java.util.*;
public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner scan=new Scanner(System.in);
        String s;
        s=scan.nextLine();
        int k=scan.nextInt();
        String small=s.substring(0,k);
        String large=s.substring(0,k);
        for(int i=1; i<=s.length()-k; i++)
        {
            String sub=s.substring(i,i+k);
            if(sub.compareTo(small)<0){
                small=sub;
            }
            if(sub.compareTo(large)>0){
                large=sub;
            }
        }
        System.out.println(small+"\n"+large);
        scan.close();
    }
}