using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace yukicoderTest
{
    class Program
    {
        static void Main(string[] args)
        {
            string n = Console.ReadLine();
            int[] itemcnt = new int[10];
            int defeattime = int.Parse(n);
            int pupcnt = 0;
            for(int i=0;i<itemcnt.Length;i++)
            {
                itemcnt[i] = 0;
            }
            for(int i=0;i<defeattime;i++)
            {
                string item = Console.ReadLine();
                string[] itemary = item.Split(' ');
                int a = int.Parse(itemary[0]);
                int b = int.Parse(itemary[1]);
                int c = int.Parse(itemary[2]);
                itemcnt[a - 1] = itemcnt[a - 1]+1;
                itemcnt[b - 1] = itemcnt[b - 1]+1;
                itemcnt[c - 1] = itemcnt[c - 1]+1;
                
            }
            int cnt = 0;
            for (int i=0;i<itemcnt.Length;i++)
            {
                while (itemcnt[i] >= 2)
                {
                    itemcnt[i] = itemcnt[i] - 2;
                    pupcnt++;
                }
                if (itemcnt[i] == 1)
                {
                    itemcnt[i]--;
                    cnt++;
                }
                if (cnt == 4)
                {
                    pupcnt++;
                    cnt = 0;
                }
            }

            Console.WriteLine(pupcnt);
        }
    }
}