You are given a string s. Among the different substrings of s, print the K-th lexicographically smallest one.

A substring of s is a string obtained by taking out a non-empty contiguous part in s. For example, if s = `ababc`, `a`, `bab` and `ababc` are substrings of s, while `ac`, `z` and an empty string are not. Also, we say that substrings are different when they are different as strings.

Let X = x_{1}x_{2}...x_{n} and Y = y_{1}y_{2}...y_{m} be two distinct strings. X is lexicographically larger than Y if and only if Y is a prefix of X or x_{j} > y_{j} where j is the smallest integer such that x_{j} \neq y_{j}.

Constraints

* 1 ≤ |s| ≤ 5000
* s consists of lowercase English letters.
* 1 ≤ K ≤ 5
* s has at least K different substrings.

Input

Input is given from Standard Input in the following format:


s
K


Output

Print the K-th lexicographically smallest substring of K.

Examples

Input

aba
4


Output

b


Input

atcoderandatcodeer
5


Output

andat


Input

z
1


Output

z
import java.util.*;
import java.lang.*;

import static java.lang.StrictMath.abs;

class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        String[] a = new String[s.length()];
        List<String> b = new ArrayList<String>();
        List<String> c = new ArrayList<String>();

        int count =0;
        for(int i =0; i< s.length();i++ ){
            for(int k=i; k<= i+5; k++){
                try {
                    b.add(s.substring(i, k));
                }catch (StringIndexOutOfBoundsException e){

                }

                count++;
            }
        }
        Collections.sort(b);
        c.add(b.get(0));

        for(int j =0; j < b.size()-1; j++){

            if(b.get(j).equals(b.get(j+1))){
                continue;
            }else{
                c.add(b.get(j+1));
            }
        }
        System.out.println(c.get(sc.nextInt()));



    }

}