memset() with 0 and 0xFF on ints – output Answer, explanation & discussion

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void) {
    int *a = malloc(4 * sizeof *a);
    if (a == NULL)
        return 1;
    memset(a, 0, 4 * sizeof *a);
    a[1] = -1;
    memset(a + 2, 0xFF, sizeof *a);
    printf("%d %d %d %d\n", a[0], a[1], a[2], a[3]);
    free(a);
    return 0;
}