using System;

class Program
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());

        string s = "";
        int up = 0;

        for(int i=0;i< n; i++)
        {
            string[] str = Console.ReadLine().Split();
            for(int j = 0; j < 3; j++)
            {
                if (str[j] == "10") str[j] = "0";
            }
            s += str[0] + str[1] + str[2];
        }

        for(int i = 0; i <= 9; i++)
        {
            int t = s.Length - s.Replace(i.ToString(), "").Length;
            if (t > 1) up += t / 2;
        }

        up += (s.Length - up * 2) / 4;

        Console.WriteLine(up);
    }
}