using System;

using System.Linq;

using System.Collections.Generic;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

    string dataJSON = @"{

    'SMCustomerID': 29187,

    'SMCo': 201,

    'CustGroup': 201,

    'Customer': 30048,

    'Active': 'Y',

    'UniqueAttchID': null,

    'Notes': null,

    'RateTemplate': '1',

    'BillToARCustomer': 30048,

    'ReportID': null,

    'CustomerPOSetting': 'N',

    'PrimaryTechnician': null,

    'InvoiceGrouping': 'C',

    'InvoiceSummaryLevel': 'C',

    'NonBillable': 'N',

    'BillingName': null,

    'BillingEmail': 'holly@meyersound.com',

    'BillingAddress1': null,

    'BillingAddress2': null,

    'BillingCity': null,

    'BillingState': null,

    'BillingPostalCode': null,

    'BillingCountry': null,

    'DeliveryMethod': 'P',

    'DeliveryTo': 'A',

    'Reviewer': null,

    'AltBillAddr': null,

    'InvoiceGroupingPOOverride': 'N',

    'Contacts': [

        {

        'SMCustomerContactID': 12,

        'ContactGroup': 201,

        'ContactSeq': 602,

        'IncludeTripCloseEmail': 'N'

        },

        {

        'SMCustomerContactID': 12,

        'ContactGroup': 201,

        'ContactSeq': 603,

        'IncludeTripCloseEmail': 'N'

        }

    ]

}";

    string dataJSON2 = @"{

    'Output': [

        {

        'HQContactID': 14022,

        'ContactGroup': 201,

        'ContactSeq': 602,

        'FirstName': 'JACK',

        'MiddleInitial': null,

        'LastName': 'MCPHAIL',

        'CourtesyTitle': null,

        'Title': null,

        'Organization': null,

        'Phone': '510-843-7573',

        'PhoneExtension': null,

        'Cell': null,

        'Fax': null,

        'Email': 'will@ljkruse.com',

        'Address': null,

        'AddressAdditional': null,

        'City': null,

        'State': null,

        'Country': null,

        'Zip': null,

        'Notes': null,

        'UniqueAttchID': null

        },

        {

        'HQContactID': 14022,

        'ContactGroup': 201,

        'ContactSeq': 603,

        'FirstName': 'PEDRO',

        'MiddleInitial': null,

        'LastName': 'MCPHAIL',

        'CourtesyTitle': null,

        'Title': null,

        'Organization': null,

        'Phone': '510-843-7573',

        'PhoneExtension': null,

        'Cell': null,

        'Fax': null,

        'Email': 'will@ljkruse.com',

        'Address': null,

        'AddressAdditional': null,

        'City': null,

        'State': null,

        'Country': null,

        'Zip': null,

        'Notes': null,

        'UniqueAttchID': null

        }

    ]

}";

        var Data = JsonConvert.DeserializeObject<dynamic>(dataJSON);

        var Data2 = JsonConvert.DeserializeObject<dynamic>(dataJSON2);

        var siteContacts =

          JArray.FromObject((object)Data.Contacts);

​

        var hqContacts =

          JArray.FromObject((object)

          Data2.Output);

​

        var mergedContacts = hqContacts

        .Where(d => siteContacts

             .Where(e => e.Value<int>("ContactSeq")

                    == d.Value<int>("ContactSeq")

              ).Any());

        foreach (var mC in mergedContacts)

            Console.WriteLine(mC.Value<string>("FirstName"));

    }

}