Directory Content Mirroring

You are writing a utility to find duplicate folders in a backup. A folder is a 'mirror' of another if it contains the exact same filenames (ignoring folder names themselves and file contents). Given a list of folders and their contents, output the name of every folder that has at least one mirror elsewhere in the list, sorted alphabetically. Example: Input: 3 FolderA: file1.txt file2.jpg FolderB: data.csv FolderC: file2.jpg file1.txt Output: FolderA FolderC