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

main()
{
	size_t n;
	char *p;

	for (;;) {
		printf("How many bytes should I allocate?\n");
		scanf("%u", &n);

		p = malloc(n);

		if (p == NULL) {
			printf("Can't allocate %u bytes.\n", n);
		} else {
			printf("%u bytes were available.  Try for more.\n", n);
			system("ps -o vsz,comm | awk 'NR == 1 || $2 == \"a.out\"'");
			free(p);
		}
	}
}