#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll inf = 2e18;
const int maxn = 5e5 + 5;
int a[maxn], b[maxn], id[maxn];
ll pre[maxn][2], suf[maxn][2], pre2[maxn][2], suf2[maxn][2];
vector<int> vec[2];
ll f[2], g[2];
struct BIT
{
int c[maxn], tot;
void add(int x, int d) { tot += d; for (; x < maxn; x += (x & -x)) c[x] += d; }
int sum(int x) { if (!x) return 0; int ans = 0; for (; x; x -= (x & -x)) ans += c[x]; return ans; }
int gol(int x) { return sum(x - 1); }
int gor(int x) { return tot - sum(x); }
}bit, bit2;
int main()
{
ios::sync_with_stdio(false), cin.tie(0);
int n; cin >> n;
for (int i = 1; i <= n; i++) cin >> a[i], b[i] = abs(a[i]), id[i] = i, bit2.add(i, 1);
sort(id + 1, id + n + 1, [&](int x, int y) { return b[x] > b[y]; });
f[0] = 0, f[1] = inf;
int l = 1;
while (l <= n)
{
int r = l;
while (r < n && b[id[l]] == b[id[r + 1]]) r++;
for (int i = l; i <= r; i++) bit2.add(id[i], -1), bit.add(id[i], 1);
if (!b[id[l]])
{
ll ans = min(f[0], f[1]);
cout << (ans == inf ? -1 : ans); return 0;
}
else
{
g[0] = g[1] = inf;
vec[0].clear(), vec[1].clear();
for (int i = l; i <= r; i++)
{
if ((a[id[i]] == b[id[i]]) ^ (id[i] & 1)) vec[0].emplace_back(id[i]);
else vec[1].emplace_back(id[i]);
}
sort(vec[0].begin(), vec[0].end()), sort(vec[1].begin(), vec[1].end());
for (int p = 0; p < 2; p++)
{
if (f[p] >= inf) continue;
int q = p ^ ((n - l + 1) & 1);
ll C = 0;
for (int o = 0; o < 2; o++)
{
pre[0][p ^ o] = pre2[0][p ^ o] = 0;
for (int i = 0; i < vec[p ^ o].size(); i++)
{
int x = vec[p ^ o][i];
pre[i + 1][p ^ o] = pre[i][p ^ o] + bit2.gol(x);
pre2[i + 1][p ^ o] = pre2[i][p ^ o] + abs(bit.gol(x) - 2 * i - o);
}
suf[0][q ^ o] = suf2[0][q ^ o] = 0;
for (int i = 0; i < vec[q ^ o].size(); i++)
{
int x = vec[q ^ o][vec[q ^ o].size() - i - 1];
suf[i + 1][q ^ o] = suf[i][q ^ o] + bit2.gor(x);
suf2[i + 1][q ^ o] = suf2[i][q ^ o] + abs(bit.gor(x) - 2 * i - o);
}
}
int nw[2] = {0, 0}, tot[2] = {(int)vec[0].size(), (int)vec[1].size()};
for (int k = 0; k <= (r - l + 1); k++)
{
int nwx = tot[0] - nw[0], nwy = tot[1] - nw[1];
if (nwx == nwy || nwx - nwy == (q ? -1 : 1))
{
ll C0 = pre[nw[0]][0] + pre[nw[1]][1] + suf[tot[0] - nw[0]][0] + suf[tot[1] - nw[1]][1];
ll C1 = pre2[nw[0]][0] + pre2[nw[1]][1] + suf2[tot[0] - nw[0]][0] + suf2[tot[1] - nw[1]][1];
g[p ^ (k & 1)] = min(g[p ^ (k & 1)], f[p] + C0 + C1 / 2);
}
if (k != (r - l + 1)) nw[p ^ (k & 1)]++;
}
}
f[0] = g[0], f[1] = g[1];
}
for (int i = l; i <= r; i++) bit.add(id[i], -1);
l = r + 1;
}
ll ans = min(f[0], f[1]);
cout << (ans == inf ? -1 : ans);
return 0;
}
