#include "shoes.h"
#include <bits/stdc++.h>
using ll = long long;
using namespace std;
const int MAXN = 2e5+5;
int n;
//vector<vector<pair<int,int>>> v(MAXN, vector<pair<int,int>>);
struct fenwick {
int tree[MAXN];
void update(int i, ll v) {
for (; i < MAXN; i += (i & -i)) tree[i] += v;
}
ll query(int i) {
ll s = 0;
for (; i > 0; i -= (i & -i)) s += tree[i];
return s;
}
} fen;
long long count_swaps(std::vector<int> s) {
n = (int)s.size() / 2;
ll ans = 0;
vector<pair<int,int>>v;
vector<pair<int,int>> ord[MAXN];
for (int i = 0; i < 2*n; ++i) {
ord[abs(s[i])].emplace_back(s[i], i);
}
for (int i = 1; i <= n; ++i) {
int m = ord[i].size();
sort(ord[i].begin(), ord[i].end());
for (int j = 0; j < m / 2; ++j) {
int fi = ord[i][j].second;
int se = ord[i][j + m/2].second;
fi++; se++;
if (fi > se) { // SHOES ARE LEFT & RIGHT SWAPPED
swap(fi, se);
ans++;
}
v.emplace_back(fi, se);
}
}
for (int i = 1; i <= 2*n; ++i) fen.update(i, 1);
sort(v.begin(),v.end());
int m = v.size();
for (int i = 0; i < m; ++i) {
int f = v[i].first;
int s = v[i].second;
ans += fen.query(s-1) - fen.query(f);
fen.update(f, -1);
fen.update(s, -1);
}
return ans;
}
