give me the total number of architect of the buildings whose one of the architect was bahāʾ al-dīn al-ʿāmilī ?
SELECT DISTINCT COUNT attr_open var_uri attr_close where brack_open var_x dbp_architect dbr_Bahāʾ_al-dīn_al-ʿĀmilī sep_dot var_x dbp_architect var_uri brack_close