3503. Longest Palindrome After Substring Concatenation I

You are given two strings, s and t. You can create a new string by selecting a substring from s (possibly empty) and a substring from t (possibly empty), then concatenating them in order. Return the length of the longest palindrome that can be formed this way. Example 1: Input: s = "a", t = "a" Output: 2 Explanation: Concatenating "a" from s and "a" from t results in "aa", which is a pali