Unique Substrings Finder

You are given a string s and an integer k. Your task is to find all unique substrings of s that have length k and print them in lexicographical order.

In other words, you need to extract all substrings substring such that:

$$\text{substring} = s[i\ldots i+k-1], \quad 0 \leq i \leq |s|-k$$

and then output the unique ones in sorted order. If no valid substring exists (i.e. when \(k > |s|\)), print an empty line.

inputFormat

The input is read from standard input and consists of two lines:

• The first line contains the string s.
• The second line contains the integer k.

It is guaranteed that s does not contain newline characters.

outputFormat

Print the unique substrings of length k found in the string s in lexicographical order, separated by a space. If there are no valid substrings, output an empty line.

abcde
3

abc bcd cde