class Solution(object):
    def findDisappearedNumbers(self, nums):
        ret = list()
        if nums is None or len(nums)==0:
            return ret
        for i in range(0,len(nums)):
            index = abs(nums[i]) - 1
            if nums[index] > 0:
                nums[index] = -nums[index]
        for i in range(0,len(nums)):
            if nums[i] > 0:
                ret.append(i+1)
        return ret
                
        