ordered_set , ordered_multiset

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;

#define int long long
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_multiset;

signed main()
{
    ordered_multiset s;
    s.insert(2);
    s.insert(7);
    s.insert(5);
    s.insert(2);
    //i - th
    for(auto i : s)
        cout << i << " ";
    cout << endl;
    int i = 2;
    auto it = s.begin();
    while(i--){
        it++;
    }
    cout << *it << endl;
    i = 2;
    cout << *s.find_by_order(i) << endl; // iterator i-th place

    int x = 5;
    cout << distance(s.begin() , s.lower_bound(x)) << endl;
    int cnt = 0;
    it = s.lower_bound(x);
    while(it != s.begin()){
        cnt++;
        it--;
    }
    cout << cnt << endl;

    cout << s.order_of_key(x) << endl; // s.lower_bound(x) - s.begin()
}