// https://www.hackerrank.com/challenges/java-string-compare/problem

import java.util.Scanner;

public class JavaSubstringComparison {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

String string = scanner.nextLine();

int k = scanner.nextInt();

scanner.close();

System.out.println(getSmallestAndLargest(string, k));

}

private static String getSmallestAndLargest(String string, int k) {

String largest;

String smallest = largest = string.substring(0, k);

for (int index = 1 ; index < string.length() - k + 1 ; index++) {

String subString = string.substring(index, index + k);

smallest = smallest.compareTo(subString) < 0 ? smallest : subString;

largest = largest.compareTo(subString) < 0 ? subString : largest;

}

return smallest + "\n" + largest;

}

}