var companyTeams = new HashSet<string>() { "Ferrari", "McLaren", "Mercedes" };
var traditionalTeams = new HashSet<string>() { "Ferrari", "McLaren" };
var privateTeams = new HashSet<string>() { "Red Bull", "Lotus", "Toro Rosso", "Force India", "Sauber" };
if (privateTeams.Add("Williams"))
Console.WriteLine("Williams added");
if (!companyTeams.Add("McLaren"))
Console.WriteLine("McLaren was already in this set");
if (companyTeams.IsSupersetOf(traditionalTeams))
Console.WriteLine("companyTeams is a superset of traditionalTeams");
Overlaps验证是否有交集
traditionalTeams.Add("Williams");
if (privateTeams.Overlaps(traditionalTeams))
Console.WriteLine("At least one team is the same with the traditional " +
"and private teams");
var allTeams = new SortedSet<string>(companyTeams);
allTeams.UnionWith(privateTeams);
allTeams.UnionWith(traditionalTeams);
Console.WriteLine();
Console.WriteLine("all teams");
foreach (var team in allTeams)
Console.WriteLine(team);
输出（有序的）：
Ferrari
Force India
Lotus
McLaren
Mercedes
Red Bull
Sauber
Toro Rosso
Williams
allTeams.ExceptWith(privateTeams);
Console.WriteLine();
Console.WriteLine("no private team left");
foreach (var team in allTeams)
Console.WriteLine(team);
