Split List of string to ignore already splitted value in c#

Question

I need to split a List connection below on the basis of value equals after cn= ex.Group Policy,Users,Administrators,Enterprise Admins in a new List which contains the unique values seen below expected value in c#

     [0]  "cn=Group Policy,cn=Users,dc=ldapdomain,dc=domain"
     [1]  "cn=Administors,cn=Users,dc=ldapdomain,dc=domain"
     [2]  "cn=Enterprise Admins,cn=LogUsers,dc=ldapdomain,dc=domain"

My expected scenario is to get a List with value below

cn[0]="Group Policy";
cn[1]="Users";
cn[2]="Administrators";
cn[3]="Enterprise Admins";
cn[4]="LogUsers";

I am trying with below code but not finding a way to split cn= 

List<string> connection = new List<string>();
            List<string> groups = new List<string>();
            groups.Add("cn=Group Policy,cn=Users,dc=ldapdomain,dc=domain");
            groups.Add("cn=Administors,cn=Users,dc=ldapdomain,dc=domain");
            groups.Add("cn=Enterprise Admins,cn=LogUsers,dc=ldapdomain,dc=domain");
            foreach(var group in groups)
            {
                group.Split("cn=");
            }

Answer 1

var list = groups
    .SelectMany(g => g.Split(','))    // split each into an array and select each item
    .Where(cn => cn.StartsWith("cn=", StringComparison.OrdinalIgnoreCase))
    .Select(cn => cn.Substring(3))    // cut off the first 3 characters
    .Distinct(StringComparison.OrdinalIgnoreCase)    // only distinct items
    .ToArray();