#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 500'000 + 10,
MAX = 1'000'000'000'000'000;
int n;
int h[N];
struct BIT {
int bit[N];
void upd(int i, int x) {
for (; i <= n; i += i & -i) bit[i] += x;
}
void assign(int i) {
for (; i <= n; i += i & -i) bit[i] = 0;
}
int que(int i) {
int ret = 0;
for (; i; i -= i & -i) ret += bit[i];
return ret;
}
} T, Z, P;
int a[N], pref[N];
int f[N][2];
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for (int i = 1; i <= n; ++i) cin >> h[i];
vector<int> allValue(n); iota(allValue.begin(), allValue.end(), 1);
sort(allValue.begin(), allValue.end(), [&](const auto& a, const auto& b) {
return make_pair(abs(h[a]), -a) > make_pair(abs(h[b]), -b);
});
for (int i = 1; i <= n; ++i) Z.upd(i, 1), P.upd(i, 1);
memset(f, 14, sizeof f);
f[0][0] = 0;
int totalSize = 0;
for (int le = 0; le < (int)allValue.size(); ++le) {
int ri = le;
while (ri < (int)allValue.size() &&
abs(h[allValue[le]]) == abs(h[allValue[ri]])) ri += 1;
vector<int> vt(allValue.begin() + le, allValue.begin() + ri);
vt.insert(vt.begin(), 0);
const int sz = vt.size() - 1;
totalSize += sz;
for (int i = 1; i <= sz; ++i) {
Z.upd(vt[i], -1);
a[i] = h[vt[i]] > 0 ? 1 : h[vt[i]] < 0 ? -1 : 0;
}
const int cntZero = Z.que(n);
int totalZero = 0;
for (int i = 1; i <= sz; ++i) totalZero += cntZero - Z.que(vt[i]);
for (int l = 0; l <= 1; ++l) {
for (int type = 0; type <= 1; ++type) {
array<deque<int>, 2> q;
for (int i = 1; i <= sz; ++i) {
q[(vt[i] ^ (a[i] == 1)) & 1].push_back(vt[i]);
pref[i] = MAX;
}
int preL = (l ^ (sz ^ type)) & 1;
vector<int> sequence;
for (int i = 1; i < sz; ++i) {
auto& ret = pref[i];
ret = pref[i - 1];
int which = (i ^ preL) & 1;
if (!q[which].size()) ret = MAX;
else {
int pos = q[which].front(); q[which].pop_front();
ret += P.que(pos) - 1 - T.que(pos - 1);
ret -= cntZero - Z.que(pos);
T.upd(pos, 1);
sequence.push_back(pos);
}
}
int total = totalZero;
if (!type) {
int i = sz;
auto& ret = pref[i];
ret = pref[i - 1];
int which = (i ^ preL) & 1;
if (!q[which].size()) ret = MAX;
else {
int pos = q[which].front(); q[which].pop_front();
ret += P.que(pos) - 1 - T.que(pos - 1);
ret -= cntZero - Z.que(pos);
T.upd(pos, 1);
sequence.push_back(pos);
}
} else {
int which = (n ^ totalSize ^ l) & 1;
if (!q[which].size()) total = MAX;
else {
int pos = q[which].front(); q[which].pop_front();
total += P.que(pos) - 1 - T.que(pos - 1) - Z.que(pos - 1);
sequence.push_back(pos);
}
}
int value = MAX;
if ((int)sequence.size() == sz) {
value = min(value, pref[sz - type] + total);
for (int i = sz - (!type ? 1 : 2); i >= 1; i -= 2) {
if (!(cntZero & 1)) swap(sequence[i - 1], sequence[i]);
int pos0 = sequence[i - 1], pos1 = sequence[i];
T.upd(pos0, -1);
T.upd(pos1, -1);
total += P.que(pos0) - 1 - T.que(pos0 - 1) - Z.que(pos0 - 1);
T.upd(pos0, 1);
total += P.que(pos1) - 1 - T.que(pos1 - 1) - Z.que(pos1 - 1);
T.upd(pos1, 1);
T.upd(pos0, -1);
T.upd(pos1, -1);
value = min(value, pref[i - 1] + total);
}
}
auto& ret = f[totalSize][l];
if (!h[vt[1]]) ret = min(ret, f[totalSize - sz][l]);
else ret = min(ret, f[totalSize - sz][preL] + value);
for (int i = 1; i <= sz; ++i) T.assign(vt[i]);
}
}
for (int i = 1; i <= sz; ++i) P.upd(vt[i], -1);
le = ri - 1;
}
int answer = min(f[totalSize][0], f[totalSize][1]);
cout << (answer >= MAX ? -1 : answer) << "\n";
}
