// Use this for initialization
    void Start()
    {
        PlayMap   playMap = Object.FindObjectOfType <PlayMap>();
        Transform grid    = transform.GetChild(0);

        foreach (Monster monsterPrefab in MonsterR.getAllMonsters())
        {
            GameObject monsterbtn = Instantiate(MonsterButton);
            monsterbtn.name = monsterPrefab.name + " button";
            monsterbtn.transform.SetParent(grid, false);
            monsterbtn.transform.localScale          = new Vector3(1, 1, 1);
            monsterbtn.GetComponent <Image>().sprite = monsterPrefab.GetComponent <SpriteRenderer>().sprite;
            monsterbtn.GetComponent <Image>().color  = monsterPrefab.GetComponent <SpriteRenderer>().color;
            monsterbtn.GetComponent <Button>().onClick.AddListener(delegate { playMap.onMonsterBtnClick(monsterPrefab); });
            monsterbtn.transform.GetChild(0).GetComponent <Text>().text = "$" + monsterPrefab.price;
        }
    }