void update(pt & cur, int query_l, int query_r)
{
if (cur->l == query_l && cur->r == query_r)
{
cur->delta++;
return;
}
int m = cur->get_m();
if (query_l < m && useful(query_l, min(query_r, m)))
{
if (cur->left == NULL)
cur->left = new node(cur->l, m);
update(cur->left, query_l, min(query_r, m));
}
if (query_r > m && useful(max(query_l, m), query_r))
{
if (cur->right == NULL)
cur->right = new node(m, cur->r);
update(cur->right, max(query_l, m), query_r);
}
}
