using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var hand = new Card[]

        {

            new Card { Rank = "A", Value = 9, Suit = 'D' },

            new Card { Rank = "A", Value = 10, Suit = 'H' },

            new Card { Rank = "T", Value = 12, Suit = 'D' },

            new Card { Rank = "T", Value = 13, Suit = 'S' },

            new Card { Rank = "5", Value = 5, Suit = 'S' },

        };

        var pairsList = hand

            .GroupBy(card => card.Rank)

            .Where(g => g.Skip(1).Any())

            .Select(o => new { Rank = o.Key, Value = o.Max(v => v.Value) });

        Result result = new Result

        {

            Ranks = pairsList.Select(o => o.Rank),

            MaxValue = pairsList.Max(o => o.Value)

        };

        Console.WriteLine($"Ranks: {string.Join(",", result.Ranks)} and max value : {result.MaxValue}");

​

    }

    public class Card

    {

        public string Rank { get; set; } 

        public int Value { get; set; }

        public char Suit { get; set; }

    }

    public class Result

    {

        public IEnumerable<string> Ranks { get; set; } 

        public int MaxValue { get; set; }

    }

}