说明：  no intro
(Have you ever played Minesweeper games? There's an operating system with this little game. What's the name of that system? - - in order to pass the game, you have to find all the mines in a NxM area. During the game, the computer will display some numbers on the map to help you determine where there is a mine. For example, here's a map of 4x4 with two mines (* denotes landmines):)