# class Solution(object):
#     def singleNum(self,nums):
#         for i in nums:
#             n = nums.count(i)
#             if n == 1:
#                 return i
#
# s=Solution()
# print(s.singleNum([1,2,2,3,3]))
#
#
# nums=[2,2,1,1,1,3]
# {1:3,2:2,3:1}

from collections import Counter
class Solution(object):
    def singleNum(self,nums):
        dict_nums = dict(Counter(nums))
        nums_list = dict_nums.keys()
        for i in nums_list:
            if dict_nums[i]==1:
                return i