#include <stdio.h>

int main()
{
    int arr[4][4] = {
          {1, 2, 3, 4},
          {4, 5, 8, 9},
          {7, 1, 0, 4},
          {6, 7, 2, 3},
    };

    for (int i = 0; i < 16; i++) {
        if (i % 4 == 0 && i)
            printf("\n");
        printf("%-3d", arr[i / 4][i % 4]);
    }
    printf("\n\n");

    for (int i = 0; i < 4 / 2; i++)
    {
        for (int j = 0; j < 4; j++)
        {
            int tmp;
            tmp = arr[(i + 2) % 4][(j + 2) % 4];
            arr[(i + 2) % 4][(j + 2) % 4] = arr[i][j];
            arr[i][j] = tmp;
        }
    }

    for (int i = 0; i < 16; i++) {
        if (i % 4 == 0 && i)
            printf("\n");
        printf("%-3d", arr[i / 4][i % 4]);
    }
    return 0;
}