c#

class Solution { public static void Main(string[] args) { int N = Convert.ToInt32(Console.ReadLine().Trim());

    List<string> l= new();

    for (int NItr = 0; NItr < N; NItr++)
    {
        string[] firstMultipleInput = Console.ReadLine().TrimEnd().Split(' ');

        string firstName = firstMultipleInput[0];

        string emailID = firstMultipleInput[1];

        if(!l.Any(i=>i==emailID) && Regex.Match(emailID, "@gmail.com").Success)
        {
            l.Add(firstName);
        }
    }

    foreach(var e in l.Order())
    {
        Console.WriteLine(e);
    }
}

}