#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> ii;
const int MAXN = 2e5 + 5;
int BIT[MAXN];
void upd(int p, int v) {
for(; p < MAXN; p += (p & -p)) BIT[p] += v;
}
int sum(int p) {
int tot = 0;
for(; p; p -= (p & -p))
tot += BIT[p];
return tot;
}
long long count_swaps(vector<int> s) {
int n = s.size() / 2;
vector<vector<int>> positions(2*n + 2);
vector<int> taken(2*n);
fill(taken.begin(), taken.end(), 0);
fill(BIT, BIT + MAXN, 0);
for(int i = 1; i <= 2*n; i++)
upd(i, 1);
for(int i = 2*n - 1; i >= 0; i--)
positions[s[i] + n].push_back(i);
long long ans = 0;
for(int i = 0; i < 2*n; i++) {
if(taken[i])
continue;
int p = positions[n - s[i]].back();
positions[n - s[i]].pop_back();
positions[s[i] + n].pop_back();
if(s[i] > 0) {
ans += sum(p);
upd(i + 1, -1);
}
else {
upd(i + 1, -1);
ans += sum(p);
}
upd(p + 1, -1);
taken[i] = taken[p] = 1;
}
return ans;
}
