Twenty Bytes Costs Thirty-Two

struct point { int x, y; char label[12]; };   /* sizeof == 20 */

struct point **v = malloc(2400000 * sizeof *v);
for (long i = 0; i < 2400000; i++)
    v[i] = malloc(sizeof(struct point));

The allocator puts an 8-byte header in front of every chunk, aligns every chunk to 16 bytes, and never hands out a chunk smaller than 32 bytes. Nothing is freed.

Ignoring the v array itself, how many bytes does the heap hold beyond the 48,000,000 bytes the program actually asked for?