make starting point 0

i have this script:
public float distance;
public Transform player;
public Text label;

	void Start () {



	}
	
	// Update is called once per frame
	void Update () {


			player.position = 0f;
			distance = Vector3.Distance (transform.position, player.position) - 593f;
			distance = distance * (-1);
			label.text = distance.ToString ("F0");
		} 		

}

this is my distance system, as you see i improvised and did -593 and *-1 since it shows on unity it starts from negative number, it starts from 0 from unity editor, but on each phone it shows a different number, -1199, 502 and so on, don’t know how to fix it, anyone?

Something like this?

public var player1 : Transform; //set player in unity gui
    player1.position.x = MCam.ScreenToWorldPoint (new Vector3 (0f, 0f, 0f)).x; // depends on the x/y/z you want the player to be on in this case you only determine the x