if (fwrite(b->B, sizeof(pb), (b->n+D-1)/D, fp) != ((b->n+D-1)/D)) {
printf("Error: cannot save parentheses sequence to file\n");
exit(1);
if (fwrite(b->B, sizeof(pb), (b->n+D-1)/D, fp) != ((b->n+D-1)/D)) {
printf("Error: cannot save parentheses sequence to file\n");
exit(1);