void
check_format(list l)
{
    integer i;
    text s;

    if (l_length(l) != 49) {
        error("wrong number of fields");
    }

    s = lf_q_text(l);
    if (length(s) != 10 || s[4] != '-' || s[7] != '-') {
        error("bad date format");
    }
    atoi(delete(delete(s, 7), 4));

    i = 1;
    while (i < 49) {
        l_r_real(l, i, atof(l_q_text(l, i)));
        i += 1;
        l_r_integer(l, i, atoi(l_q_text(l, i)));
        i += 1;
    }
}

integer
main(void)
{
    integer goods;
    file f;
    list l;
    record r;

    goods = 0;

    f_affix(f, "readings.txt");

    while (f_list(f, l, 0) != -1) {
        if (!trap(check_format, l)) {
            if (r_key(r, l_head(l))) {
                v_form("duplicate ~ line\n", l_head(l));
            } else {
                integer i;

                r_put(r, l_head(l), 0);
                i = 2;
                while (i < 49) {
                    if (l_q_integer(l, i) != 1) {
                        break;
                    }
                    i += 2;
                }
                if (49 < i) {
                    goods += 1;
                }
            }
        }
    }

    o_integer(goods);
    o_text(" good unique lines\n");

    return 0;
}