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);
    }
}

}

C#

using System.Text.RegularExpressions;

int N = int.Parse(Console.ReadLine()); List names = new List();

Regex gmailPattern = new Regex(@"@gmail.com$");

for (int i = 0; i < N; i++) { var parts = Console.ReadLine().Split(' '); string firstName = parts[0]; string emailID = parts[1];

if (gmailPattern.IsMatch(emailID))
    names.Add(firstName);

}

foreach (var name in names.OrderBy(n => n)) Console.WriteLine(name);

Using Python and RegEx

if __name__ == '__main__':
    N = int(input().strip())

    res = []
    pattern = re.compile(r'@gmail\.com$')
    
    for _ in range(N):
        firstName, emailID = input().strip().split()
        if pattern.search(emailID):
            res.append(firstName)
    
    for x in sorted(res):
        print(x)

in python code: . . . . . . . . if name == 'main': N = int(input().strip()) gmail = []

for N_itr in range(N): first_multiple_input = input().rstrip().split()

firstName = first_multiple_input[0]

emailID = first_multiple_input[1]



if '@gmail.com' in emailID:
    gmail.append(firstName)

gmail.sort()

for name in gmail: print(name)

python 3 solution:

if __name__ == '__main__':
N = int(input().strip())
gmail = []

for N_itr in range(N):
    first_multiple_input = input().rstrip().split()

    firstName = first_multiple_input[0]

    emailID = first_multiple_input[1]



    if '@gmail.com' in emailID:
        gmail.append(firstName)

gmail.sort()

for name in gmail:
    print(name)