A user interface displays markdown price recommendations for a given set of retail merchandise aimed at attaining optimal gross margin while clearing merchandise from a retailer by a given date and adhering to the retailer’s business rules and operational constraints. Each of the non-volatile memory devices has: a word gate formed above a semiconductor layer with a gate insulating layer interposed; an impurity layer formed in the semiconductor layer; and control gates in the form of side walls formed along both side surfaces of the word gate. The second beam is generated substantially simultaneously with the inspection beam.