Thank you for viewing. Regarding shipping: For purchases made between the evening of the 1st (Monday) and the 7th (Sunday), shipping will be on the 13th (Saturday) or 14th (Sunday). For purchases made between the evening of the 8th (Monday) and the 14th (Sunday), shipping will be on the 20th (Saturday) or 21st (Sunday). For multiple book purchases: Shipping costs may be discounted, so please comment. (Discounts may not be possible depending on the thickness of the books.) If you purchase multiple books without commenting, we may ship them together at the original price. Difficulty Level Indication for All Problems All problems are marked with a 10-level difficulty rating based on the correct answer rate. You can easily see the "Basic Problems" to solve, the "Standard Problems" to become able to solve, and the "Advanced Problems" you don't need to solve yet, allowing students to efficiently practice entrance exam questions at their level.