import java.util.Scanner;

public class Solution {

public static String getSmallestAndLargest(String s, int k) {
    String smallest = "";
    String largest = "",s2;
    int j=0,s1=0,e=k;
    int n=s.length()-k+1;
    String []ss=new String[s.length()-k+1];
    while(j!=(s.length()-k+1)){
        ss[j]=s.substring(s1,e);
        s1++;
        e++;
        j++;
    }
    for(int i=0;i<n-1;i++){
        for(j=i+1;j<n;j++){
            if(ss[i].compareTo(ss[j])>0){
        s2=ss[i];
                ss[i]=ss[j];
                ss[j]=s2;

            }
        }
    }
    smallest=ss[0];
    largest=ss[n-1];
    return smallest + "\n" + largest;
}