static void Main(string[] args) { Song song1 = new Song("bla bla", 7, "22.02.2002", "h"); Node <Song> songs = new Node <Song>(song1); Node <Song> song2 = new Node <Song>(new Song("Elections 2019", 14, "17.09.2019", "q")); songs.SetNext(song2); Disk disk1 = new Disk(songs, "1.1.2002", 10000, "l"); Node <Disk> disks = new Node <Disk>(disk1); Singer singer1 = new Singer(songs, disks); Console.WriteLine("commends are: 1. check_len, then a space, if you want a song, write s and then a name of a song, if you want a disk, write the name of the disk.\n2. buy_disk and the the name of the disk.\n3. search, then a space and words, and the result will be a song that contains these words.\n 4. buy, a space and the name of the disk\n5. search, a space, and words in the song"); string commend = Console.ReadLine(); string[] commend_and_params = commend.Split(); if (commend_and_params[0] == "check_len") { if (commend_and_params[1] == "s") { Node <Song> song = songs; while (song != null) { if (commend_and_params[2] == song.GetValue().GetName()) { Console.WriteLine("len is " + song.GetValue().GetLen()); } song = song.GetNext(); } } else { Node <Disk> disk = disks; while (disk != null) { if (commend_and_params[1] == disk.GetValue().GetName()) { Console.WriteLine("len is " + disk.GetValue().GetLen()); } disk = disk.GetNext(); } } } else if (commend_and_params[0] == "buy") { Console.WriteLine("bought successfully"); } else { Node <Song> song = songs; while (song != null) { if (song.GetValue().GetWords().Contains(commend_and_params[1])) { Console.WriteLine("song is " + song.GetValue().GetName()); } song = song.GetNext(); } } }