using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
class MainClass
{

    public static Dictionary<string, bool> valid_combination = new Dictionary<string, bool>(){
        { "BCHJ", false },
        { "DEFG", false }
    };

    public static void Main(string[] args)
    {
        string S = "1A 2F 1C";
        int N = 2;
        int result = solution(N, S);
        Console.WriteLine(result);
        Console.ReadKey();
    }

    public static int solution(int N, string S)
    {

        if (String.IsNullOrEmpty(S))
            return 2 * N;
        int result = 0;
        string[] SArray = S.Split(' ');
        SArray = SArray.OrderBy(x => x).ToArray();
        int length = SArray.Length;
        for (int i = 1; i <= N; i++)
        {
            int valid_combination_count = valid_combination.Count;
            for (int j = 0; j < length; j++)
            {
                string seat = SArray[j];
                string a = seat.ToCharArray()[0].ToString();
                if (a.Equals(i.ToString()))
                {

                    char[] sChar = seat.Substring(1).ToCharArray();
                    foreach (string item in valid_combination.Keys.ToList())
                    {
                        if (item.ToArray().Contains(sChar[0]) && !valid_combination[item])
                        {
                            valid_combination_count--;
                            valid_combination[item] = true;
                        }
                    }
                }
            }

            result += valid_combination_count;

        }
        return result;

    }
}