using System;

namespace YukiCorderNo29_20170924 {
    class Program {
        static void Main(string[] args) {
            string N;
            N = Console.ReadLine();

            int[] itemBox = new int[Int32.Parse(N) * 3];

            for (int i = 1; i <= Int32.Parse(N); i++) {
                string[] inputItem = Console.ReadLine().Split(' ');
                for (int j = 0; j < 3; j++) {
                    itemBox[(i - 1) * 3 + j] = Int32.Parse(inputItem[j]);
                    //Console.WriteLine((i - 1) * 3 + j + ": " + itemBox[(i - 1) * 3 + j]);
                }
            }

            int powerUp = 0;
            int num = 0;
            int amariNum = 0;

            for (int i = 1; i <= 10; i++) {
                num = 0;
                for (int j = 0; j < itemBox.Length; j++) {
                    if (itemBox[j] == i) {
                        num++;
                        //Console.WriteLine("numAdd:"+ i);
                    }
                    //Console.WriteLine(num);
                }
                powerUp += num / 2;
                amariNum += num % 2;
            }
            powerUp += amariNum / 4;
            Console.WriteLine(powerUp);
        }
    }
}