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.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String args[]) {

		Scanner sc = new Scanner(System.in);

		String s = sc.nextLine();
		int K = sc.nextInt();

		List<String> sub = new ArrayList<>();
		char fast_char = 'z';

		for(int i=0;i<s.length();i++) {
			if(s.charAt(i) <= fast_char) {
				fast_char = s.charAt(i);
			}else if(sub.size() > K) {
				continue;
			}

			for(int j=i;j<=Math.min(s.length(),i+5);j++) {
				String temp = s.substring(i, j);
				if(!sub.contains(temp)) {
					sub.add(temp);
				}
			}
		}

		Collections.sort(sub);

		System.out.println(sub.get(K));
	}
}
