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[] gets = new int[3];
            int[] items = new int[10];
            Console.ReadLine();
            int ans = 0;
            while (true)
            {
                var tmp = Console.ReadLine();
                if (string.IsNullOrEmpty(tmp)) break;
                gets = tmp.Split(' ')
                    .Select(x=>x.Length==2?9:x[0]-49).ToArray();
                Parallel.ForEach(gets, get =>
                {
                    items[get]++;
                    if (items[get] == 2)
                    {
                        items[get] = 0;
                        ans++;
                    }
                });
            }
            ans += items.Sum()/4;
            Console.WriteLine(ans);
        }
    }
}