Pointers and multidimensional arrays in C++

I have this piece of code:

#include <iostream>
int main()
{
int ia[3][4]; // array of size 3; each element is an array of ints of size 4
int (*p)[4] = ia; // p points to an array of four ints
p = &ia[2]; // p now points to the last element in ia
return 0;
}

How does p point to the last element in ia?