Good afternoon guys, I recently started working with the structure "Ordered Set" and "Unordered Muilti-set", and I noticed that in the second it is not possible to delete elements.

How it looks in my code:

#include <ext/pb_ds/assoc_container.hpp>

#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;

#define order_set tree<int, null_type,less, rb_tree_tag,tree_order_statistics_node_update>

So if you know what the problem is, could you help?