using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        List<xType> theX = new List<xType> {  new xType { a = 1, b = 2, n = 3, z = 7}, 

                                           new xType { a = 2, b = 3, n = 2, z = 2},

                                           new xType { a = 1, b = 2, n = 4, z = 7},

                                           new xType { a = 1, b = 2, n = 5, z = 2},

                                     };

        List<yType> theY = new List<yType> {  new yType { a = 1, b = 5, c = 3}, 

                                           new yType { a = 2, b = 2, c = 2},

                                           new yType { a = 1, b = 5, c = 4},

                                     };

        List<pType> theP = new List<pType> {  new pType { a = 1, b = 5, z = 3}, 

                                           new pType { a = 2, b = 2, z = 2},

                                           new pType { a = 1, b = 5, z = 4},

                                     };

        List<dType> theD = new List<dType> {  new dType { a = 1, b = 5, z = 7}, 

                                           new dType { a = 2, b = 2, z = 7},

                                           new dType { a = 1, b = 5, z = 5},

                                     };

        int[] myN = new int[] {3, 4};

        var result = from typeX in theX

            join typeY in theY on typeX.a equals typeY.a

            join typeP in theP on typeX.b equals typeP.b where myN.Contains(typeX.n)

            join typeD in theD on typeX.z equals typeD.z

            select typeX;

        result.Dump();

    }

    public class xType

    {

        public int a {get;set;}

        public int b {get;set;}

        public int n {get;set;}

        public int z {get;set;}

    }

    public class yType

    {

        public int a {get;set;}

        public int b {get;set;}

        public int c {get;set;}

    }

    public class pType

    {

        public int a {get;set;}

        public int b {get;set;}

        public int z {get;set;}

    }

    public class dType

    {

        public int a {get;set;}

        public int b {get;set;}

        public int z {get;set;}

    }

}