package com.company.HackerRank;
    
    import java.util.Arrays;
    import java.util.Scanner;
    
    public class SubstringComparisons {
        // https://www.hackerrank.com/challenges/java-string-compare/problem
    
        public SubstringComparisons() {
            // Brute force is O(n^2) by looping through array and using String.compareTo()
            // We can achieve O(nlogn) by sorting first
    
            Scanner scan = new Scanner(System.in);
            String s = scan.next();
            int k = scan.nextInt();
            scan.close();
    
            // Populate array
            String[] array = new String[s.length() - k + 1];
            for (int i = 0; i < s.length() - k + 1; i++) {
                String substring = s.substring(i, i + k);
                array[i] = substring;
            }
    
            // Sort array and write out answer
            Arrays.sort(array);
            System.out.println(array[0] + "\n" + array[array.length - 1]);
        }
    }