An imaging unit images an object to be imaged and acquires image data. An output value is first set and a root-mean-square value corresponding to the current is further obtained. At this point, a point amount is determined by the game server based on time points at which the attack button is operated or the like. The method includes identifying quality-control problems associated with the mail set, separating the mail set from other mail during a second processing step, and separately processing the mail set from the other mail.