using System;
using System.Linq;

class Program
{
    public void Solve()
    {
        int N = int.Parse(Console.ReadLine());
        int[] abc;
        int[] item = new int[11];
        int powerup = 0;

        for (int i = 0; i < N; i++)
        {
            abc = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();

            for (int j = 0; j < abc.Length; j++)
            {
                item[abc[j]]++;

                if (0 < item[abc[j]] / 2)
                {
                    powerup += item[abc[j]] / 2;
                    item[abc[j]] %= 2;
                }
            }
        }
        powerup += item.Sum() / 4;

        Console.WriteLine(powerup);
    }

    static void Main()
    {
        var solver = new Program();
        solver.Solve();
    }
}