int num = 3;
    string output= "Gem numbers = 3";
    void OnTriggerEnter  (Collider other)
    {
	if (other.tag == "Picker")
        {
            num--;
            output = "Gem numbers = " + num.ToString();
            if (num == 0) output = "你贏了！";
           Destroy (other.gameObject);
        }
    }