from collections import defaultdict
class Solution(object):
    def findLongestWord(self, s, d):
        """
        :type s: str
        :type d: List[str]
        :rtype: str
        """
        return min(filter(lambda x: self.is_subseq(x, s), d) + [''],
            key=lambda ans: (-len(ans), ans)
        )

    def is_subseq(self, word, s):
        it = iter(s)
        return all(char in it for char in word)