using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var people = new[]

        {

           new {Id = 6000, Name = "Jennifer", Age = 21}, 

           new {Id = 6001, Name = "Alton", Age = 22},

           new {Id = 6003, Name = "Milford", Age = 23}

        };

        var ids = people.Select(person => person.Id);

        foreach (var id in ids)

        {

            Console.WriteLine(id);

        }

    }

}