摘要：
There are nn models in the shop numbered from 11 to nn , with sizes s1,s2,…,sns1,s2,…,sn . Orac will buy some of the models and will arrange them in t 阅读全文
摘要：
Orac is studying number theory, and he is interested in the properties of divisors. For two positive integers aa and bb , aa is a divisor of bb if and 阅读全文