摘要：
E. Music Festival The boy Vitya loves to listen to music very much. He knows that $n$ albums are due to be released this Friday, $i$-th of which conta 阅读全文
摘要：
C. The Very Beautiful Blanket Kirill wants to weave the very beautiful blanket consisting of $n \times m$ of the same size square patches of some colo 阅读全文