nullreferenceexception object reference not set to an instance of an object

Please Help

#pragma strict
public var damage :int;

function Start () {
	damage = damage;

}

function OnTriggerEnter(p : Collider){
	if(p.tag == "Enemy")
	{
	GetComponent(EnemyHealth).HP -=damage;
	Debug.Log("The Enemy got " + damage + " damage");
	}

}

this line is the problem but i don’t know how to fix

GetComponent(EnemyHealth).HP -=damage;

GetComponent().HP -= damage;

#pragma strict
public var damage :int;

function Start () {
	damage = damage;

}

function OnTriggerEnter(p : Collider){
	if(p.tag == "Enemy")
	{
	GetComponent<EnemyHealth>().HP -= damage;
	Debug.Log("The Enemy got " + damage + " damage");
	}

}