Given two strings s and t which consist of only lowercase letters.

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

Find the letter that was added in t.

Example:

Input:

s = "abcd"

t = "abcde"

Output:

e

Explanation:

'e' is the letter that was added.

from collections import Counter

class Solution(object):

    def findTheDifference(self, s, t):

        """

        :type s: str

        :type t: str

        :rtype: str

        """

        cs=Counter(s)

        ct=Counter(t)

        for k in ct:

            if cs[k]!=ct[k]:

                return k