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
    {
        private static void Main(string[] args)
        {

            int[] items = new int[10];
            string[] gets = new string[3];
         int num=int.Parse(   Console.ReadLine());
         string[] inputs=new string[num];
            int ans = 0;
            int sum = 0;
            int p = 0;
            int c = 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]++;
                    

                }
                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);
        }
    }


    
}