这个P[4][4] 内存上到底是怎么分配的?

#include <stdio.h>
int main()
{
int a[5][5] = {
1,2,3,4,5,
6,7,8,9,10,
11,12,13,14,15,
16,17,18,19,20,
21,22,23,24,25
};
int (*p)[4];
p = a;
printf("%d, %d\n", a[4][2], p[4][2]);
printf("%d\n", &p[4][2] - &a[4][2]);
}