// include
#include<bits/stdc++.h>
#include "shoes.h"
using namespace std;
// random
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// templates
template<class X, class Y>
bool maximize(X &x, const Y &y) {
if (y > x) {
x = y;
return (true);
} else return (false);
}
template<class X, class Y>
bool minimize(X &x, const Y &y) {
if (y < x) {
x = y;
return (true);
} else return (false);
}
// define
#define fi first
#define se second
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define eb emplace_back
#define upb upper_bound
#define lwb lower_bound
#define left VAN
#define right TAN
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).begin(),(a).end()
#define sort_and_unique(a) sort(all(a));(a).resize(unique(all(a))-a.begin())
#define max_ max_element
#define min_ min_element
// another define
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
// limit
const int oo = 2e9;
// function
void yesno(bool x) {
cout << (x ? "YES\n" : "NO\n");
}
// FenwickTree
struct FenwickTree {
vector<ll> ft;
int from, to;
FenwickTree() {}
FenwickTree(int _from, int _to): from(_from), to(_to) {
// set initial value
ft.assign(to - from + 5, 0);
}
private:
void Upd(int p, ll v) {
p = max(p, from);
for (int j = p; j <= to; j += (j & (-j)))
ft[j] += v;
}
ll Get(int p) {
ll result = 0;
p = min(p, to);
for (int j = p; j >= from; j -= (j & (-j)))
result += ft[j];
return (result);
}
public:
void upd(int p, ll v) {
Upd(p, v);
}
ll get(int p) {
return (Get(p));
}
};
ll count_swaps(vector<int> a) {
int n = (int)a.size() / 2;
ll ans = 0;
vector<vector<int>> p(2 * n + 5);
for (int i = 2 * n - 1; i >= 0; i--) {
p[n + a[i]].push_back(i + 1);
//cout << a[i] << ' ' << n + a[i] << '\n';
}
FenwickTree ft(1, 2 * n);
for (int i = 0; i < 2 * n; i++) {
bool ok = false;
if ((int)p[n + a[i]].size()) {
//cout << i << ' ' << a[i] << ' ' << p[n + a[i]].back() << '\n';
if (p[n + a[i]].back() == i + 1) {
ok = true;
}
}
if (ok) {
p[a[i] + n].pop_back();
int l = i + 1;
//cout << a[i] << '\n';
int r = p[-a[i] + n].back();
p[-a[i] + n].pop_back();
if (a[i] < 0) {
ans += r - l - 1 - ft.get(r) + ft.get(l - 1);
ft.upd(r, 1);
} else {
ans += r - l - ft.get(r) + ft.get(l - 1);
}
ft.upd(r, 1);
}
}
return (ans);
}
