solution

import java.util.Scanner;

public class Solution {

public static String getSmallestAndLargest(String s, int k) {
    String smallest = s.substring(0,k);
    String largest = s.substring(0,k);

    for(int i=0;i<=s.length()-k;i++){
        String subString=s.substring(i,i+k);
        if(subString.compareTo(smallest)<0){
            smallest=subString;
        }
        if(subString.compareTo(largest)>0){
            largest=subString;
        }
    }

    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));
}

}