using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using System.Text;

public class Program

{

    public static void Main()

    {

            var json = @"

{  

   ""root"":{  

      ""first"":{  

         ""first1"":{  

            ""value"":""1""

         },

         ""first2"":{  

            ""value"":""2""

         },

         ""first3"":{  

            ""value"":""3""

         }

      }

    }

}";

​

        var jobject = JObject.Parse (json);

        var sb = new StringBuilder ();

        RecursiveParse (sb, jobject);

        Console.WriteLine (sb.ToString());

    }

    public static void RecursiveParse(StringBuilder sb, JToken token)

    {

        foreach (var item in token.Children()) {

            if (item.HasValues)

            {

                RecursiveParse (sb, item);

            } else {

                sb.AppendLine (item.Path);

            }

        }

    }   

}