public static void Main()
{
var n = Convert.ToInt32(Console.ReadLine());
string[] cTemp = Console.ReadLine().Split(' ');
Int16[] c = new Int16[cTemp.Length + 1];
for (int i = 0; i <= cTemp.Length - 1; i++)
{
c[i] = Convert.ToInt16(cTemp[i]);
}
Int32 sum = 0;
List <Int16> result = c.Distinct().ToList();
for (int i = 0; i <= result.Count - 1; i++)
{
var tmp = result[i];
var res = (from t in c where t.Equals(tmp) select t).Count();
if (res > 1)
{
if (Math.Floor(Convert.ToDecimal(res / 2)) != Math.Ceiling(Convert.ToDecimal(res / 2)))
{
res = res - 1;
}
sum += res / 2;
}
}
Console.WriteLine(sum);
Console.ReadLine();
}