Time Limit: 2000MS Memory Limit: 65536KTotal Submissions: 20116 Accepted: 6325. Alice and Bob often play games on chessboard. One day, Alice draws a board with size M * N. She wants Bob to use a lot of cards with size 1 * 2 to cover the board. However, she thinks it too easy to bob, so she makes some holes on the board .We call a grid, which doesn’t contain a hole, a normal grid. Bob has to follow the rules below: 1. Any normal grid should be covered with exactly one card. 2. One card should cover exactly 2 normal adjacent grids.An invalid solution, because the hole of red color is covered with a card.An invalid solution, because there exists a grid, which is not covered.Your task is to help Bob to decide whether or not the chessboard can be covered according to the rules above.If the board can be covered, output "YES". Otherwise, output "NO". 阅读全文