import java.io.; import java.util.;

public class Solution {

public static void main(String[] args) {
    Scanner scanner=new Scanner(System.in);
    String s=scanner.next();
    int k=scanner.nextInt();
    ArrayList<String> sub=new ArrayList<>();
    for(int i=0;i<s.length();i++){
        if(i < s.length()-(k-1)){
           String subVals=s.substring(i,i+k); 
           sub.add(subVals);

        }
    }
    Collections.sort(sub);
    String first=sub.get(0);
    String last=sub.get(sub.size()-1);
    System.out.print(first + "\n" + last);
}

}