dynamic sort-fenwick using PBDS

sf_dynamic.cpp

#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
using ll=long long;
template<class T,class U>
using ord_map=tree<T,U,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
template<class T,class U>
using ord_multimap=tree<T,U,less_equal<T>,rb_tree_tag,tree_order_statistics_node_update>;

template<int sz>
struct sf_dynamic
{
    ord_multimap<ll,null_type>fen[sz];
    void add(int i,ll x)
    {
        while(i<sz)
        {
            fen[i].insert(x);
            i+=i&-i;
        }
    }
    void erase(int i,ll x)
    {
        while(i<sz)
        {
            fen[i].erase(fen[i].find_by_order(fen[i].order_of_key(x)));
            i+=i&-i;
        }
    }
    ll qry_g(int i,ll x)
    {
        ll ans=0;
        while(i>0)
        {
            ans+=size(fen[i])-fen[i].order_of_key(x+1);
            i-=i&-i;
        }
        return ans;
    }
    ll qry_ge(int i,ll x)
    {
        ll ans=0;
        while(i>0)
        {
            ans+=size(fen[i])-fen[i].order_of_key(x);
            i-=i&-i;
        }
        return ans;
    }
    ll qry_l(int i,ll x)
    {
        ll ans=0;
        while(i>0)
        {
            ans+=fen[i].order_of_key(x);
            i-=i&-i;
        }
        return ans;
    }
    ll qry_le(int i,ll x)
    {
        ll ans=0;
        while(i>0)
        {
            ans+=fen[i].order_of_key(x+1);
            i-=i&-i;
        }
        return ans;
    }
    ll qry_eq(int i,ll x)
    {
        ll ans=0;
        while(i>0)
        {
            ans+=fen[i].order_of_key(x+1)-fen[i].order_of_key(x);
            i-=i&-i;
        }
        return ans;
    }
};