#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include "/home/eagle/ioi19/d1/debug.h"
#else
#define debug(...) void(37)
#endif
struct Fenwick {
vector<int> sum;
int n;
Fenwick(int _n) : n(_n) {
sum.resize(n + 1);
for (int i = 1; i <= n; ++i) {
sum[i] = 1 << __builtin_ctz(i);
}
}
void modify(int x) {
x += 1;
while (x <= n) {
sum[x] -= 1;
x += x & -x;
}
}
int get(int x) {
x += 1;
int res = 0;
while (x > 0) {
res += sum[x];
x -= x & -x;
}
return res;
}
};
long long count_swaps(std::vector<int> S) {
int N = int(S.size()) / 2;
vector<queue<int>> g(2 * N + 1);
vector<int> match(2 * N, -1);
for (int i = 2 * N - 1; i >= 0; --i) {
int need = -S[i] + N;
if (g[need].empty()) {
g[S[i] + N].push(i);
} else {
match[i] = g[need].front();
g[need].pop();
}
}
debug(match);
Fenwick fenw(2 * N);
long long ans = 0;
for (int i = 0; i < 2 * N; ++i) {
if (match[i] != -1) {
fenw.modify(match[i]);
fenw.modify(i);
ans += fenw.get(match[i]) + (S[i] > 0);
}
}
return ans;
}
