using System;

using System.Collections.Generic;

using System.Linq;

​

public class A

{

    public List<B> Data

    {

        get;

        set;

    }

}

​

public class B

{

    public C Data

    {

        get;

        set;

    }

}

​

public class C

{

    public List<E> Data

    {

        get;

        set;

    }

}

​

public class E

{

    public int Id

    {

        get;

        set;

    }

​

    public string Name

    {

        get;

        set;

    }

​

    public override string ToString()

    {

        return string.Format("Id={0},Name={1}", Id, Name);

    }

}

​

public class Program

{

    public static void Main()

    {

        var sampleData = new List<A>{new A{Data = new List<B>{new B{Data = new C{Data = new List<E>{new E{Id = 1, Name = "John Smith"}, new E{Id = 1, Name = "Fred Daniel"}, }}}}}};

        Console.WriteLine("Test 1");

        var getOneId = GetEById(1, sampleData);

        if (getOneId != null)

        {

            Console.WriteLine(getOneId.ToString());

        }

        Console.WriteLine();

        Console.WriteLine("Test 2");

        var getAllId = GetAllEById(1, sampleData);

        foreach (var item in getAllId)

        {

            Console.WriteLine(item.ToString());

        }

    }

​

    private static E GetEById(int id, List<A> data)

    {

        return data.SelectMany(a => a.Data.SelectMany(b => b.Data.Data)).FirstOrDefault(e => e.Id == id);

    }

​

    private static IEnumerable<E> GetAllEById(int id, List<A> data)

    {

        return data.SelectMany(x => x.Data.SelectMany(y => y.Data.Data)).Where(x => x.Id == id);

    }

}