摘要：
Polycarp knows that if the sum of the digits of a number is divisible by 3, then the number itself is divisible by 3. He assumes that the numbers, the 阅读全文
摘要：
Arkady invited Anna for a dinner to a sushi restaurant. The restaurant is a bit unusual: it offers nn pieces of sushi aligned in a row, and a customer 阅读全文