How to change scene by id?

Hi.

I want to change a scene using the id of each one in the build settings, something like this:

public function BotonConceptos()

{
	Application.LoadLevel(sceneid+1);
}

or

public function BotonConceptos()

{
	Application.LoadLevel(sceneid-1);
}

I think is making the scene a var and send it to other scenes, but, i have proved a lot of things and i can´t.

Thanks so much for your help!

UnityEngine.SceneManagement.SceneManager.LoadScene(index);

hexagonius thanks a lot.

I have this.

using UnityEngine;
using System.Collections;
using UnityEngine.SceneManagement;



public class Botones2 : MonoBehaviour {

	public int y;
	private static int p;
	
	void Awake(){
		
		DontDestroyOnLoad(gameObject);
		
	}
	
	public void Boton1(){
	
	y = SceneManager.GetActiveScene().buildIndex;
	SceneManager.LoadScene (Random.Range(0,4));
		
	}
		
	public void Boton2(){
	
	p=gameObject.getComponent(y);
	SceneManager.LoadScene (y);
	
		
	}
	
}

The button 2 dont take the int saved in button 1. Can u help me please? i´ve tried a lot and no solution yet