How Repeatedly Game Object store in array??How Identify??

i take a one prefab(paint)

and store in array but problem is there repeatedly prefab store??

when my player(cube) move forward then store the gameobject in array

when my player(cube) move backward then store the gameobject in array

how to detect player when back then already fillup object not store in array??

Referance:

 public GameObject[] array;
         int temp = 0;
     
            array[temp] = Instantiate<GameObject>(paint, position,Quaternion.identity);
            temp++;
             if(temp==100)
             {
                     GameOver();
             }