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

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String smallest = "";
        String largest = "";
        String originalString = scan.nextLine();
        int substringLength = scan.nextInt();
        List<String> wordsList = new ArrayList<>();

        // Iterate through the string, extracting substrings of the desired length
        for (int i = 0; i <= originalString.length() - substringLength; i++) {
            String substring = originalString.substring(i, i + substringLength);
            wordsList.add(substring);
        }
        Collections.sort(wordsList);
        String firstWordOfFirstSentence = wordsList.get(0).split("\\s+")[0];
        String lastSentence = wordsList.get(wordsList.size() - 1);
        String lastWordOfLastSentence = lastSentence.split("\\s+")[lastSentence.split("\\s+").length - 1];   
        System.out.println(firstWordOfFirstSentence); 
        System.out.println(lastWordOfLastSentence);
    }
}