在8×8的国际象棋棋盘上，如果在某些位置放置若干个马之后，使整个棋盘中任意空位置上所放置的棋子均能被这些马吃掉，则把这组放置的棋子称为一个满覆盖。求解一个最小满覆盖-On 88 chess board, if placed after several horses at certain locations, so that the whole board to any empty position on the placed pieces can be eaten by the horses, the group placed this piece called a full coverage. Solving a minimum full coverage