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
{
  unsafe  internal class Program
    {
        //29
      unsafe  private static void Main(string[] args)
        {
            unsafe
            {
                int* items = stackalloc int[10];
                string [] gets=new string[3];
                Console.ReadLine();
                int ans = 0;
                int sum = 0;
                while (true)
                {
                    var tmp = Console.ReadLine();
                    if (string.IsNullOrEmpty(tmp)) break;
                    gets = tmp.Split(' ');
                    var name = gets[0][0];
                    *(items +((gets[0].Length==2?9: gets[0][0]-49)))+=1;
                    *(items +((gets[1].Length==2?9: gets[1][0]-49)))+=1;
                    *(items +((gets[2].Length==2?9: gets[2][0]-49)))+=1;
                }                                                    
                for (int i = 0; i < 10; i++)
                {
                   ans+= *(items + (i))>>1;
                    sum += *(items + (i)) % 2;
                }
                sum >>= 2;
                Console.WriteLine(ans+sum);
            }
        }
    }
}