Destroy object after 5 collisions

Hi this is my first post so go easy on me. I have searched but cant find info on a way to count the number of hits an object receives and and destroy it after it has been hit say 5 time.

My guess is that I need to count the number of collisions in a variable and then when the variable = 5 destroy object. But I can figure out how to do that. Oh yes and the object to destroy is an instance.

I have been trying to adapt this script that destroys after a period of time but no joy so thought i would put my hand up.

// Instantiate a rigidbody then set the velocity

var projectile : Rigidbody;
var destroyTimeMin = 2.0;
var destroyTimeMax = 5.0;
var pop : ParticleEmitter;

function OnCollisionEnter (col : Collision) {
  Instantiate(pop, transform.position, transform.rotation);
}

function Update () {
  // Ctrl was pressed, launch a projectile
  if (Input.GetButtonDown("Fire1")) {
    // Instantiate the projectile at the position and rotation of this transform
    var clone : Rigidbody;
    clone = Instantiate(projectile, transform.position, transform.rotation);

    // Give the cloned object an initial velocity along the current
    // object's Z axis
    clone.velocity = transform.TransformDirection (Vector3.forward * 10);    

    Destroy(clone.gameObject, Random.Range(destroyTimeMin, destroyTimeMax));
  }
}

for seeing if the object is getting hit 5 times I’d think you’d simple do this…

var hit = 0;

function OnCollisionEnter(){
    hit +=1;
    checkhit();
}

function checkhit(){
    if(hit == 5){
        Destroy(gameObject);
    }
}