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

public class Solution {

public static void main(String[] args) {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
String ss;
int k;
int ct=0;
Scanner sc=new Scanner(System.in);
ss=sc.nextLine();
k=sc.nextInt();
String[] arr=new String[ss.length()-k+1];
int st=0,ed=k-1;

    int m=0;
    while(m!=(ss.length()-k+1))
    {

        arr[m]=ss.substring(st,ed+1);
        st++;
        ed++;
        m++;
    }
    // for(int i=0;i<ss.length()-k;i++)
    // {
    //     System.out.print(arr[i]+" ");
    // }
    String small=arr[0];
    String large=arr[ss.length()-k];
    for(int i=0;i<ss.length()-k+1;i++)
    {
        if(small.compareTo(arr[i])<0)   small=arr[i];
    }
    for(int i=0;i<ss.length()-k+1;i++)
    {
        if(large.compareTo(arr[i])>0)   large=arr[i];
    }
    System.out.println(large+"\n"+small);
}   

}