static void Main(string[] args)
{
int[] cases = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray<int>();
int[] people = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).Where(x => x <= 5 - cases[1]).ToArray<int>();
Console.WriteLine(people.Length / 3);
Console.ReadLine();
}
