using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace yukicore
{
    internal class Program
    {
        //29
        private static void Main(string[] args)
        {
           
                int[] items =new int[10];
                string [] gets=new string[3];
                Console.ReadLine();
                int ans = 0;
                int sum = 0;
                while (true)
                {
                    var tmp = Console.ReadLine();
                    if (string.IsNullOrEmpty(tmp)) break;
                    gets = tmp.Split(' ');
                    var name = gets[0][0];
                    items [gets[0].Length==2?9: gets[0][0]-49]++;
                    items [gets[1].Length==2?9: gets[1][0]-49]++;
                    items [gets[2].Length==2?9: gets[2][0]-49]++;
                }                                                    
                for (int i = 0; i < 10; i++)
                {
                   ans+= items  [i]>>1;
                    sum += items[i] % 2;
                }
                sum >>= 2;
                Console.WriteLine(ans+sum);
            }
        }
    
}