using System.Collections.Generic;
using System;

public class Hello
{
    static void Main()
    {
        var n = int.Parse(Console.ReadLine().Trim());
        string[] line = Console.ReadLine().Trim().Split(' ');
        var a = Array.ConvertAll(line, int.Parse);
        getAns(n, a);
    }
    static void getAns(int n, int[] a)
    {
        var d = new Dictionary<int, int>();
        foreach (var x in a)
        {
            if (d.ContainsKey(x)) d[x]++;
            else d[x] = 1;
        }
        var c = 0;
        foreach (var x in d.Values) c += x / 2;
        Console.WriteLine(c);
    }
}