using System;

using System.Xml;

using System.Xml.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string xml =

        @"<Container>

          <Encounters>

            <Encounter>

              <a>a1</a>

              <b>b1</b>

            </Encounter>

            <Encounter>

              <a>a2</a>

              <b>b2</b>

            </Encounter>

          </Encounters>

        </Container>";

        // Convert XML to a JObject

        JObject root = JObject.Parse(JsonConvert.SerializeXNode(XElement.Parse(xml)));

        // Move the array of Encounter objects up one level

        JProperty encounters = ((JObject)root["Container"]).Property("Encounters");

        encounters.Value = encounters.Value["Encounter"];

        // Output the JSON

        string json = root.ToString();

        Console.WriteLine(json);

    }

}