#include "shoes.h"
using namespace std;
#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
typedef long long ll;
#define dbg(x) cerr << #x << " = " << x << "\n";
using namespace __gnu_pbds;
typedef tree<
ll,
null_type,
less<ll>,
rb_tree_tag,
tree_order_statistics_node_update
> ordered_set;
long long count_swaps(std::vector<int> a) {
ll n = a.size() / 2;
map<ll, deque<ll>> mp;
for (ll i = 0; i < 2 * n; i++) {
mp[a[i]].push_back(i);
}
ordered_set s;
for (ll i = 0; i < 2 * n; i++) {
s.insert(i);
}
ll res = 0;
while (s.size()) {
// dbg(s.size());
auto x = *s.begin();
ll sz = a[x];
mp[sz].pop_front();
ll other = mp[-sz].front();
mp[-sz].pop_front();
res += s.order_of_key(other) - (sz < 0);
s.erase(x);
s.erase(other);
}
return res;
}
