Find Unique Substrings

You are given a string s and an integer k. Your task is to find all unique substrings of s that have a length exactly equal to k and print them in lexicographical (i.e., \(\text{lexicographical}\)) order.

Note that if k is less than or equal to 0 or greater than the length of s, then the output should be empty.

Example:

• Input: s = "abcabc", k = 3
• Output: abc bca cab

The output substrings should be separated by a space.

inputFormat

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

1. The first line contains the string s.
2. The second line contains the integer k.

outputFormat

Print the unique substrings of length k from s in lexicographical order. The substrings should be separated by a space. If there are no valid substrings, print nothing.

abcabc
3

abc bca cab