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"

def findTheDifference(self, s: str, t: str) -> str:
	t = list(t)
	d = Counter(t)
	for i in s:
		d[i] -= 1
		if d[i] == 0:
			del d[i]
	return list(d.keys())[0]