说明：  将一个5X5的矩阵中最大的元素放在中心，4个角分别放4个最小的元素（顺序为从左到右，从上到下顺序依次从小到大存放），写一函数实现之。用main函数调用。
(A 5X5 matrix in the center of the largest element on the four corners were placed four minimal elements (the order from left to right, top to bottom in the order from small to large storage), write a function to achieve it. With the main function call.)