how make the coin not increased when the player touch them more than one?

hallo master…
i need some help i have a script ( score script) and i want to make the coin when the player touch the coin more than one, the coin can’t increase my score. i need only a touch to increase the score. more than that the value does not increase.

how can i setup my script??? please

public int scoreTogive = 100;

private ScoreManager theScoreManager;


// Use this for initialization
void Start () {

	theScoreManager = FindObjectOfType<ScoreManager> ();
}

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

}
void OnTriggerEnter2D (Collider2D bojo)
{
	if (bojo.gameObject.name == "Player")
	{
		theScoreManager.AddScore(scoreTogive);

		}
	}

}

Destroy the coin after adding the scoreTogive.