说明：  将一个5*5的矩阵中最大的元素放在中心，四个角分别放四个最小的元素（顺序从左到右，从上到下顺序依次从小到大存放）
(A 5* 5 matrix elements of the largest on the center, four corners, respectively, put the four smallest element (sequence from left to right, from top to bottom the order from small to large storage))