Pasted

DirectoryInfo myInfo = new DirectoryInfo(DbFolderPath);
FileInfo[] myDbFiles = myInfo.GetFiles("*.db", SearchOption.TopDirectoryOnly);
string myFileName;
foreach (FileInfo item in myDbFiles) {
    myFileName = Path.GetFileNameWithoutExtension(item.Name);
    if (int.TryParse(myFileName, out int myDummy)) {
        Result.Add(item.FullName);
    }
}