A store promotes merchandise in the following ways: at any time of the year, either with seasonal sales, with holiday sales, or both  Each promotion lasts for one month  In any month, if the store wants to clear a certain category of goods, it announces a seasonal sale; if there is a holiday in a certain month and there are still items left in the warehouse, it announces an intervening sale
However, there are no festivals in November and there are no items left in the warehouse this month
If a month doesn't have a seasonal sale, there must be a holiday sale this month.