using System;
using System.Linq;
using System.Collections.Generic;
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;
using Autodesk.Revit.UI.Selection;

public void main(UIApplication uiApplication)
{
	var uidoc = uiApplication.ActiveUIDocument;
    var doc = uidoc.Document;
    var reference=uidoc.Selection.PickObject(ObjectType.Element);
}