random level loader?

i already have a game set up and ready to be played, but i have one problem.

the character starts in a small room, and when they exit through a door, it should take them to 1 of 12 different level outcomes. i have the level loading script, but i’m not sure how to splice the random generator into the level loader. anyone know how?

function Start() {
number = Random.Range(1,12);
}

function OnCollisionEnter (collision : Collision) {
    if (collision.gameObject.name=="Player")
    	Start();
    	
        Application.loadLevel(1);
}

Application.loadLevel(Random.Range(1,13));

Note that the scripting reference statement for Random.Range() of integers:

Returns a random integer number between min [inclusive] and max [exclusive]

So it will never return the last value in the range.