rp(list l)
{
    integer a, i;
    data b;
    index x;

    a = l[0];
    x[a] = a;
    for (, a in l) {
        x[a == x.back + 1 ? x.high : a] = a;
    }
    for (i, a in x) {
        b.form(a - i < 2 ? a - i ? "~,~," : "~," : "~-~,", i, a);
    }

    b.delete(-1);
}

main(void)
{
    o_(rp(list(0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22,
               23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39)),
       "\n");

    0;
}