using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;

public class Range
{
    public long m_start;
    public long m_end;
    public long m_candidate;
}

[ServiceContractAttribute(ConfigurationName = "mapReplaceContract")]
public interface IRangeInterface
{
    [OperationContractAttribute]
    long? findDivisor(Range range);
}

public class RangeImplementation : IRangeInterface
{
    public long? findDivisor(Range range)
    {
        for (long k = range.m_start; k <= range.m_end; ++k)
        {
            long res = range.m_candidate / k;
            if (res * k == range.m_candidate)
            {
                return res;
            }
        }
        return null;
    }
}

class Program
{
    static void Main()
    {
        Console.Write("Enter port number: "); 
        string sPort = Console.ReadLine();
        sPort = sPort.Trim();
        string URI = "net.tcp://localhost:" + sPort + "/AnyLocallyUniqueName";
        using (ServiceHost serviceHost = new ServiceHost(typeof(RangeImplementation)))
        {
            serviceHost.AddServiceEndpoint(typeof(IRangeInterface), new NetTcpBinding(), new Uri(URI));
            serviceHost.Open();
            Console.WriteLine("Service is running on {0}", URI);
            Console.WriteLine("Hit <ENTER> to kill it.");
            Console.ReadLine();
        }
    }
}