using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        string[] fof = new[] { "Ryan", "Kieran", "Mark", "Jimmy" };

        FriendOrFoe(fof);

    }

    public static IEnumerable<string> FriendOrFoe (string[] names) {

​

         List<string> newfof = new List<string>();

        foreach (string element in names) {

            if (element.Length == 4) {

                newfof.Add(element);

            }

            newfof.GetEnumerator();

        }

        return newfof;

    }

}