using System;

using System.Collections.Generic;

​

​

public delegate bool MeDelegate(int i);

public class Program

{

    public static bool LessThanFive(int n) { return n < 5; }

    public static bool LessThanTen(int n) { return n < 10; }

    public static bool GreatherThanThirteen(int n) {return n > 13; }

    public static IEnumerable<int> GetAllNumbersThroughGauntLet(IEnumerable<int> numbers, MeDelegate gauntlet)

    {

        foreach (int number in numbers)

        {

            if(gauntlet(number))

                yield return number;

        }

    }

    public static void Main()

    {

        int [] numbers = new int[] {1, 3, 15, 14, 2, 4};

        IEnumerable<int> result = GetAllNumbersThroughGauntLet(numbers, GreatherThanThirteen);

        foreach (int number in result)

        {

            Console.WriteLine("number:{0}", number);

        }

    }

}