#include "shoes.h"
#include <iostream>
#include <cmath>
typedef long long ll;
using namespace std;
struct FTree {
vector<ll> nums;
int size=1;
void init(int n) {
while(size < n) size *= 2;
nums.resize(size+1);
}
void set(int n) {
while(n <= size) {
nums[n]++;
n += (n & -(n));
}
}
ll get(int n) {
ll ans = 0;
while(n > 0) {
ans += nums[n];
n -= (n & -(n));
}
return ans;
}
void print() {
for(int i = 0; i <= size; i++) cout << nums[i] << ' ';
cout << '\n';
}
};
vector<vector<int>> ct;
bool taken[200002];
ll count_swaps(vector<int> s) {
int n = s.size();
n /= 2;
ll ans = 0;
ct.resize(2*n+1);
for(int i = 2*n-1; i >= 0; i--) {
ct[n+s[i]].push_back(i+1);
}
FTree ft;
ft.init(2*n);
for(int i = 0; i < 2*n; i++) {
if(taken[i]) continue;
int x = s[i];
int a = ct[n+x].back(), b = ct[n-x].back();
ct[n+x].pop_back(); ct[n-x].pop_back();
if(x < 0) ans--;
int bb = ft.get(b), aa = ft.get(a);
ans += std::abs(b-a) - std::abs(bb - aa);
ft.set(b);
ft.set(a);
taken[a-1] = taken[b-1] = true;
}
return ans;
}
