string[] topics = {"operating systems", "Memory Management", "Fetch-Decode-Execute Cycle", "Scheduling", "BIOS", "Virtual machines"};
string[] ntopics = {"Packets", "TCPIP", "Network Security", "HashTables", "Search Engines", "Compression", "Encryption", "Hardware", "OSI", "Databases", "Boolean Algebra", "Graphs","binary Tree", "Networks", "DataStructures", "ACID", "Normalisation"};
Random rnd = new Random();
public static void Main()
Program program = new Program();
x = rnd.Next(0,topics.Length-1);
Console.WriteLine(ntopics[x]);