#include <sys/types.h>
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char *argv[]) {
    size_t amt;
    char *a, *p;
    if (argv[1]) amt = (size_t)atoi(argv[1]);
    else amt = 1024 * 1024;
    if (!(a = malloc(amt))) {
        fprintf(stderr, "failed to malloc %u bytes\n", amt);
        return 1;
    }
    for (p = a; p < a + amt; ++p) *p = (char)p;
    return 0;
}