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++;
                p++;

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

                }
                p++;
                p++;

                if (p + 2 == lng)
                {
                    items[9]++;
                    continue;

                }
                else
                    items[tmp[p] - 49]++;
            }

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