import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        var entry = new Scanner(System.in);
        String s = entry.next();
        int k = entry.nextInt();
        
        System.out.println(getSmallestAndLargest(s, k));
    }
    
    private static String getSmallestAndLargest(String s, int k){
        var lista = new ArrayList<String>();
        
        for (int i = 0; i <= s.length()-k; i++){
            String subS = s.substring(i, i+k);
            lista.add(subS);
        }
        
        Collections.sort(lista);
        
        return lista.get(0) + "\n" + lista.get(lista.size()-1);
    }
}