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 are substrings of s, while
z and an empty string are not.
Also, we say that substrings are different when they are different as strings.
Let X = x1x2...xn and Y = y1y2...ym be two distinct strings. X is lexicographically larger than Y if and only if Y is a prefix of X or xj > yj where j is the smallest integer such that xj ≠ yj.
- 1 ≤ |s| ≤ 5000
- s consists of lowercase English letters.
- 1 ≤ K ≤ 5
- s has at least K different substrings.
- 67 points will be awarded as a partial score for passing the test set satisfying |s| ≤ 50.
Input is given from Standard Input in the following format:
Print the K-th lexicographically smallest substring of K.
Sample Input 1
Sample Output 1
s has five substrings:
Among them, we should print the fourth smallest one,
Note that we do not count
Sample Input 2
Sample Output 2
Sample Input 3
Sample Output 3