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;
            int p = 0;
                while (true)
                {
                    var tmp = Console.ReadLine();
                    if (string.IsNullOrEmpty(tmp)) break;
                    p = 0;
                    int lng = tmp.Length;
                    if (tmp[p + 1] - 49 < -1)
                    {
                    items[tmp[p] - 49]++;
                }
                    else
                    {
                        items[9]++;
                        p++;
                  
                    }
                    p++;

                    if (tmp[p + 1] - 49 < -1)
                    {
                        items[tmp[p] - 49]++;
                    }
                    else
                    {
                        items[9]++;
                        p++;

                    }
                    p++;

                    if (tmp[p + 1] - 49 < -1)
                    {
                        items[tmp[p] - 49]++;
                    }
                    else
                    {
                        items[9]++;
                        p++;

                    }
                    p++;
            }
            for (int i = 0; i < 10; i++)
                {
                   ans+= items  [i]>>1;
                    sum += items[i] & 0x1;
                }
                sum >>= 2;
                Console.WriteLine(ans+sum);
            }
        }
    
}