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 = 1 ; i + k <= s.length() ; i++) {

        String myWord = s.substring(i,i+k);

        if (smallest.compareTo(myWord) > 0) {

            smallest =  myWord ;

        } 

        if (largest.compareTo(myWord) < 0) {

            largest = myWord ;

        }
    }


    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));
}

}