public static String getSmallestAndLargest(String s, int k) { String smallest = ""; String largest = "";

// Complete the function
// 'smallest' must be the lexicographically smallest substring of length 'k'
// 'largest' must be the lexicographically largest substring of length 'k'
int n=s.length();
smallest=s.substring(0,k);
largest=s.substring(0,k);

for(int i=0;i<n-k;i++) //selection sort
{
    String sm = s.substring(i,i+k);
    String lg = s.substring(i,i+k);
    for(int j=i+1;j<n+1-k;j++) {
        String t = s.substring(j,j+k);
        if(t.compareTo(sm)<=0) 
            sm=t;
        if(t.compareTo(lg)>=0)
            lg = t;
    }
    if(sm.compareTo(smallest)<=0)
        smallest=sm;
    if(lg.compareTo(largest)>=0)
        largest=lg;
}

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));

}