C# LINQ - Get One Record The Meets Condition, If Not Just Select One Record

Hi Experts!

Need your help with the following query.

In jobHistories, for each City, for each Perid, how would you filter the linq query to return the following condition: if Hired = "Y" then select one of the record with Hired = "Y" and ignore the rest of the records for PerId. If there are no Hired= "Y" then just select one record for the PerId

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace UnitTestProject2
{

    [TestClass]
    public class UnitTest3
    {
        internal class JobHistory
        {
            public int PerId;
            public string JobTitle;
            public string Address;
            public string Hired;
            public string City;
            public Nullable<System.DateTime> CreatedOn;
        }

        [TestMethod]
        public void Extract_HiredThenEverythingElse_CorrectPicks2()

        {
            // Arrange
            List<JobHistory> jobHistories = new List<JobHistory>()
            {
                new JobHistory() {PerId = 1, JobTitle = "Knight", Address = "123 Street", Hired = "Y", City = "Yokohama", CreatedOn = new DateTime(2011, 6, 1)},
                new JobHistory() {PerId = 1, JobTitle = "Cook", Address = "234 Street", Hired = "Y", City = "Yokohama", CreatedOn = new DateTime(2012, 6, 1)},
                new JobHistory() {PerId = 1, JobTitle = "Mechanic", Address = "345 Street", Hired = "N", City = "Yokohama", CreatedOn = new DateTime(2012, 12, 1)},

                new JobHistory() {PerId = 2, JobTitle = "Knight", Address = "123 Street", Hired = "N", City = "Fukuoka", CreatedOn = new DateTime(2011, 6, 1)},
                new JobHistory() {PerId = 2, JobTitle = "Cook", Address = "234 Street", Hired = "N",  City = "Fukuoka", CreatedOn = new DateTime(2012, 6, 1)},
                new JobHistory() {PerId = 2, JobTitle = "Mechanic", Address = "345 Street", Hired = "",  City = "Fukuoka", CreatedOn = new DateTime(2012, 12, 1)},

                new JobHistory() {PerId = 3, JobTitle = "Knight", Address = "123 Street", Hired = "",  City = "Osaka", CreatedOn = new DateTime(2011, 6, 1)},
                new JobHistory() {PerId = 3, JobTitle = "Cook", Address = "234 Street", Hired = "", City = "Osaka", CreatedOn = new DateTime(2012, 6, 1)},
                new JobHistory() {PerId = 3, JobTitle = "Mechanic", Address = "34r Street", Hired = "", City = "Osaka", CreatedOn = new DateTime(2014, 12, 1)}
            };

            // Act
            //For each City, for each PerId, if Hired = "Y" then select one of the record with Hired = "Y". If there are no Hired= "Y" then just select one record
            var groupedByCity = (from city in jobHistories
                                   group city by city.City into islandGroup
                                   select islandGroup).ToList();

            var groupedByPerson = (from byCity in groupedByCity
                                     select from item in byCity
                                            group item by item.PerId into personGroup
                                            select personGroup.First()).ToList(); //<-- ????

            var flattened = from grouping in groupedByPerson
                            from item in grouping
                            select item;

            var results = flattened.ToList();

            //Assert
            //these are the records should return from the linq query
            //new JobHistory() { PerId = 1, JobTitle = "Knight", Address = "123 Street", Hired = "Y", City = "Yokohama", CreatedOn = new DateTime(2011, 6, 1) },
            //new JobHistory() { PerId = 2, JobTitle = "Knight", Address = "123 Street", Hired = "N", City = "Fukuoka", CreatedOn = new DateTime(2011, 6, 1) },
            //new JobHistory() { PerId = 3, JobTitle = "Knight", Address = "123 Street", Hired = "", City = "Osaka", CreatedOn = new DateTime(2011, 6, 1) },

        }

    }
}

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