摘要：
You're given an array a1,…,ana1,…,an of nn non-negative integers. Let's call it sharpened if and only if there exists an integer 1≤k≤n1≤k≤n such that 阅读全文
摘要：
Vasya came to the store to buy goods for his friends for the New Year. It turned out that he was very lucky — today the offer "kk of goods for the pri 阅读全文