def dfs(self, word, i, node, cnt):
        if cnt > 2 or not node: return False
        if i == len(word): return node.isEnd
        
        idx = ord(word[i]) - ord("a")
        if self.dfs(word, i + 1, node.child[idx], cnt):
            return True
            
        for j in range(26):
            if j != idx and self.dfs(word, i + 1, node.child[j], cnt + 1):
                return True
        return False