i'm tring to change the restarter script by unity to instead load the next level

i want to be able to get the build number of the scene so i can then load the next level. this will allow me to use this script as a prefab therefore have infinite levels and not have to mannually change the build number ps. by build number i mean the number next to the scenes in build settings

using System; using UnityEngine;

namespace UnityStandardAssets._2D {

 public class Finisher : MonoBehaviour
 {
     public int CurrentLevel;
     private void OnTriggerEnter2D(Collider2D other)
     {
         if (other.tag == "Player")
         {
             CurrentLevel = Application.loadedLevelName; //instead of getting the name i want the build number
             Application.LoadLevel(CurrentLevel + 1);
         }
     }
 }

}