exit(EXIT_FAILURE);
    }
    // read data from dataname into input
    char *input = NULL;
    size_t ilen = slurp(&input, dataname);

    // call the right function
    void (*p)(char *, size_t) = select(y, d);
    void (*p)(char *, size_t) = aocselect(y, d);
    if (p) p(input, ilen);
    else fprintf(stderr, "Impossible!\n");
    free(input);
}