389. Find the Difference

You are given two strings s and t.

String t is generated by random shuffling string s and then add one more letter at a random position.

Return the letter that was added to t.

Example 1:

Input: s = "abcd", t = "abcde"

Output: "e"

Explanation: 'e' is the letter that was added.

Example 2:

Input: s = "", t = "y"

Output: "y"

Example 3:

Input: s = "a", t = "aa"

Output: "a"

Example 4:

Input: s = "ae", t = "aea"

Output: "a"

Constraints

• 0 <= s.length <= 1000
• t.length == s.length + 1
• s and t consist of lower-case English letters.