using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        List<PostCodeSum> postCodeSumTotals = new List<PostCodeSum>(); 

        postCodeSumTotals.Add(new PostCodeSum(){TotalCost=12,PostCode="1"});

        postCodeSumTotals.Add(new PostCodeSum(){TotalCost=122,PostCode="11"});

        postCodeSumTotals.Add(new PostCodeSum(){TotalCost=123,PostCode="12"});

        postCodeSumTotals.Add(new PostCodeSum(){TotalCost=129,PostCode="13"});

        postCodeSumTotals.Add(new PostCodeSum(){TotalCost=124,PostCode="14"});

        postCodeSumTotals.Add(new PostCodeSum(){TotalCost=125,PostCode="15"});

        postCodeSumTotals.Add(new PostCodeSum(){TotalCost=1255,PostCode="16"});

        postCodeSumTotals.Add(new PostCodeSum(){TotalCost=126,PostCode="17"});

        var top5 = postCodeSumTotals.OrderByDescending(a => a.TotalCost).Take(5); 

        foreach(var item in top5)

            Console.WriteLine("total: {0} and postcode:{1}",item.TotalCost,item.PostCode);

    }

    public class PostCodeSum 

    {

        public decimal TotalCost; 

        public string PostCode;

    }

}