Given two strings X and Y of lengths m and n respectively, find the length of the smallest string which has both, X and Y as its sub-sequences.
Note: X and Y can have both uppercase and lowercase letters.

Example 1

Input:
X = abcd, Y = xycd
Output: 6
Explanation: Shortest Common Supersequence
would be abxycd which is of length 6 and
has both the strings as its subsequences.

Example 2

Input:
X = efgh, Y = jghi
Output: 6
Explanation: Shortest Common Supersequence
would be ejfghi which is of length 6 and
has both the strings as its subsequences.

Your Task:
Complete shortestCommonSupersequence() function that takes X, Y, m, and n as arguments and returns the length of the required string.

Expected Time Complexity: O(Length(X) * Length(Y)).
Expected Auxiliary Space: O(Length(X) * Length(Y)).

Constraints:
1<= |X|, |Y| <= 100