#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
namespace testcaseCheck {
const int SUBTASK = 6;
bool permutationsOfShoes(vector<int> S, int N) {
vector<int> V;
for (int i = 1; i <= N; ++i) {
V.push_back(-i);
V.push_back(i);
}
sort(S.begin(), S.end());
sort(V.begin(), V.end());
for (int i = 0; i < 2 * N; ++i) {
if (S[i] != V[i]) {
return false;
}
}
return true;
}
void run(std::vector<int> S) {
assert(1 <= SUBTASK && SUBTASK <= 6);
assert(S.size() % 2 == 0);
int N = S.size() / 2;
assert(1 <= N && N <= 100000);
map<int, int> sizeToOccurences;
for (int s : S) {
sizeToOccurences[abs(s)] += s / abs(s);
}
for (pair<int, int> occurences : sizeToOccurences) {
assert(occurences.second == 0);
}
if (SUBTASK == 1) {
assert(N == 1);
}
if (SUBTASK == 2) {
assert(N <= 8);
}
if (SUBTASK == 3) {
for (int s : S) {
assert(abs(s) == abs(S[0]));
}
}
if (SUBTASK == 4) {
for (int i = 0; i < N; ++i) {
assert(abs(S[i]) == S[i + N]);
}
}
if (SUBTASK == 5) {
assert(N <= 1000);
}
}
}
long long count_swaps(vector<int> S) {
testcaseCheck::run(S);
int N = S.size() / 2;
if (N == 1) {
if (S[0] < S[1]) {
return 0;
}
return 1;
}
long long countswaps = 0;
for (int i = 0;i < N;i ++) {
countswaps += i;
}
return countswaps;
}
