Given two strings S and T, find length of the shortest subsequence in S which is not a subsequence in T. If no such subsequence is possible, return -1. A subsequence is a sequence that appears in the same relative order, but not necessarily contiguous. A string of length n has different possible subsequences.

Example 1:
Input:
S = "babab"
T = "babba"
Output:
3
Explanation:
There are no subsequences of S with
length less than 3 which is not a
subsequence of T. "aab" is an example of
a subsequence of length 3 which isn't a
subsequence of T.
Example 2:
Input:
S = "babhi"
T = "babij"
Output:
1
Explanation:
"h" is a subsequence of S that is
not a subsequence of T.

Your Task:
You don't need to read input or print anything. Your task is to complete the function shortestUnSub() which takes two Strings S, and T as input and returns the shortest Uncommon Subsequence.

Expected Time Complexity: O(|S|^{2}|T|)
Expected Auxiliary Space: O(|S||T|)

Constraints:
1 <= |S|, |T| <= 500

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