int main() {
    int rows = 4;
    int cols = 6;
    int num;
    int **arr = (int**) malloc(rows * sizeof(int*));

    for(size_t i = 0; i < rows; ++i) {
        arr[i] = (int*) malloc(cols * sizeof(int));
        printf("%p is arr[%d]\n", arr[i], i);
    }
    printf("\n");

    for(size_t i = 0; i < rows; ++i) {
        for(size_t j = 0; j < cols; ++j) {
            num = i * j;
            arr[i][j] = num; // (1)
            printf("%d | ", arr[i][j]);
        }
        printf("\n");
    }
    printf("\n");

    for(size_t i = 0; i < rows; ++i) {
        printf("%p is arr[%d]\n", arr[i], i);
        free(arr[i]);
        printf("%d is freed\n", i);
    }

    free(arr);
    return 0;
}