void split(pnode t, pnode &l, pnode &r, int64_t k)
{
    if (!t)
    {
        l = 0;
        r = 0;
        return;
    }
    int64_t lc = 0;
    push(t);
    if (t->l) lc = t->l->c;
    if (lc < k)
    {
        split(t->r, t->r, r, k - lc - 1);
        l = t;
        update(t);
    }
    else
    {
        split(t->l, l, t->l, k);
        r = t;
        update(t);
    }
}

void merger(pnode &t, pnode l, pnode r)
{
    if (!l)
    {
        t = r;
        return;
    }
    if (!r)
    {
        t = l;
        return;
    }
    push(r);
    push(l);
    if (l->prior < r->prior)
    {
        merger(l->r, l->r, r);
        t = l;
        update(l);
    }
    else
    {
        merger(r->l, l, r->l);
        t = r;
        update(r);
    }
}