Longest Common Prefix

class Solution:
    def longestCommonPrefix(self, strs: List[str]) -> str:

        length = min([len(x) for x in strs])
        N = len(strs)

        for l in range(length):
            flag = True
            for i in range(1, N):
                if strs[i][l] != strs[0][l]:
                    flag = False
                    break

            if not flag:
                return strs[0][:l]

        return strs[0][:length]