public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        ArrayList<String> fileNames = new ArrayList<>();
        while (true) {
            String fileName = reader.readLine();
            if (fileName.equals("exit")) {
                reader.close();
                break;
            }
            fileNames.add(fileName);
        }
        Collections.sort(fileNames);
        String fileResult = fileNames.get(0).substring(0, fileNames.get(0).length() - 6);
        BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileResult)));
        for (int i = 0; i < fileNames.size(); i++) {
            BufferedReader readerFiles = new BufferedReader(new InputStreamReader(new FileInputStream(fileNames.get(i))));
            while (readerFiles.ready()) {
                bufferedWriter.write(readerFiles.read());
            }
            readerFiles.close();
        }
        bufferedWriter.close();
    }
}