Given a list of sorted characters letters containing only lowercase letters, and given a target letter target, find the smallest element in the list that is larger than the given target.

Letters also wrap around. For example, if the target is target = 'z' and letters = ['a', 'b'], the answer is 'a'.

Examples:

Input:

letters = ["c", "f", "j"]

target = "a"

Output: "c"

Input:

letters = ["c", "f", "j"]

target = "c"

Output: "f"

Input:

letters = ["c", "f", "j"]

target = "d"

Output: "f"

Input:

letters = ["c", "f", "j"]

target = "g"

Output: "j"

Input:

letters = ["c", "f", "j"]

target = "j"

Output: "c"

Input:

letters = ["c", "f", "j"]

target = "k"

Output: "c"

Note:

1. letters has a length in range [2, 10000].
2. letters consists of lowercase letters, and contains at least 2 unique letters.
3. target is a lowercase letter.

class Solution(object):

    def nextGreatestLetter(self, letters, target):

        """

        :type letters: List[str]

        :type target: str

        :rtype: str

        """

        i=0

        n=len(letters)

        o=ord(target)

        while i<n:

            if ord(letters[i])>o:

                return letters[i]

            else:

                i+=1

        if i==n:

            return letters[0]