#include "shoes.h"
#include<bits/stdc++.h>
#define int long long
using namespace std;
int n, bit[200005];
void update(int p, int v)
{
for(int i = p; i <= n; i += i & (-i)) bit[i] += v;
}
int query(int p)
{
int ans = 0;
for(int i = p; i > 0; i -= i & (-i)) ans += bit[i];
return ans;
}
bool used[200005];
int count_swaps(vector<int32_t> s) {
memset(used, 0, sizeof(used));
n = s.size();
vector<list<int>> f(n+1);
for(int i = 0; i < s.size(); i++) f[s[i]+n/2].push_back(i);
int ans = 0;
for(int i = 1; i <= n; i++) update(i, 1);
for(int i = 0; i < n; i++) if(used[i] == 0){
used[i] = 1;
int val = s[i]+n/2, target = -s[i]+n/2;
f[val].pop_front();
int p = f[target].front(); f[target].pop_front();
used[p] = 1;
update(i+1, -1); update(p+1, -1);
ans += query(p+1);
if(s[i] > 0 && s[p] < 0) ans++;
//cerr<<"A"<<i<<" "<<p<<" "<<ans<<endl;
}
return ans;
}
