#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
const int maxn = 5e5 + 5;

stack<pii> st;
vector<int> v1, v2;

ll dp[maxn][2];
int a[maxn], id[maxn];
bool cmp(int x, int y) { return abs(a[x]) > abs(a[y]); }

struct BIT
{
	int c[maxn];
	void add(int x, int 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; }
}bitn, bita, bitp;

int main()
{
//	ios::sync_with_stdio(false);
//	cin.tie(0);
	
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> a[i], id[i] = i, bita.add(i, 1);
	sort(id + 1, id + n + 1, cmp);
	
	int l = 1, c = 0;
	memset(dp, 0x3f, sizeof(dp));
	dp[0][0] = 0;
	while (l <= n)
	{
		c++;
		int r = l;
		while (r < n && abs(a[id[r + 1]]) == abs(a[id[l]])) r++;
		v1.clear(); v2.clear();
		while (st.size()) st.pop();
		
		if (!a[id[l]])
		{
			dp[c][0] = dp[c - 1][0];
			dp[c][1] = dp[c - 1][1];
			break;
		}
		else
		{
			for (int i = l; i <= r; i++)
			{
				bita.add(id[i], -1);
				if ((a[id[i]] > 0) ^ (id[i] & 1)) v1.emplace_back(id[i]);
				else v2.emplace_back(id[i]);
			}
			sort(v1.begin(), v1.end());
			sort(v2.begin(), v2.end());
			int sz1 = v1.size(), sz2 = v2.size();
			if (abs(sz1 - sz2) > 2) continue;
			
			bool lop = 0, rop = (n - l + 1) & 1;
			int pos1 = sz1 - 1, pos2 = sz2 - 1;
			
			ll res = 0;
			for (int i = 1; i <= r - l + 1; i++)
			{
				if (rop ^ (i & 1))
				{
					if (pos1 < 0) break;
					st.push(make_pair(v1[pos1], 1));
					res += bitn.sum(v1[pos1]);
					res += bita.sum(n) - bita.sum(v1[pos1]);
					bitn.add(v1[pos1--], 1);
				}
				else
				{
					if (pos2 < 0) break;
					st.push(make_pair(v2[pos2], 0));
					res += bitn.sum(v2[pos2]);
					res += bita.sum(n) - bita.sum(v2[pos2]);
					bitn.add(v2[pos2--], 1);
				}
			}
			
			int nx1 = pos1, nx2 = pos2; pos1 = pos2 = -1;
			if (nx1 == -1 && nx2 == -1) dp[c][0] = min(dp[c][0], dp[c - 1][0] + res);
			for (int i = 1; i <= r - l + 1; i++)
			{
				if (st.size() > (r - l + 1 - i))
				{
					pii tmp = st.top(); st.pop();
					if (tmp.second) nx1++;
					else nx2++;
					bitn.add(tmp.first, -1);
					res -= bitn.sum(tmp.first);
					res -= bita.sum(n) - bita.sum(tmp.first);
					res -= bitp.sum(n) - bitp.sum(tmp.first);
				}
				
				if (lop ^ (i & 1))
				{
					if (nx1 != nx2 + 1 || nx1 + nx2 + 2 != i) continue;
					if (pos2 < nx2)
					{
						pos2++;
						res += bita.sum(v2[pos2]);
						res += bitn.sum(v2[pos2]);
						res += bitp.sum(n) - bitp.sum(v2[pos2]);
						bitp.add(v2[pos2], 1);
					}
					if (pos1 < nx1)
					{
						pos1++;
						res += bita.sum(v1[pos1]);
						res += bitn.sum(v1[pos1]);
						res += bitp.sum(n) - bitp.sum(v1[pos1]);
						bitp.add(v1[pos1], 1);
					}
					dp[c][1] = min(dp[c][1], dp[c - 1][0] + res);
				}
				else
				{
					if (nx1 != nx2 || nx1 + nx2 + 2 != i) continue;
					if (pos1 < nx1)
					{
						pos1++;
						res += bita.sum(v1[pos1]);
						res += bitn.sum(v1[pos1]);
						res += bitp.sum(n) - bitp.sum(v1[pos1]);
						bitp.add(v1[pos1], 1);
					}
					if (pos2 < nx2)
					{
						pos2++;
						res += bita.sum(v2[pos2]);
						res += bitn.sum(v2[pos2]);
						res += bitp.sum(n) - bitp.sum(v2[pos2]);
						bitp.add(v2[pos2], 1);
					}
					dp[c][0] = min(dp[c][0], dp[c - 1][0] + res);
				}
			}
			for (int i = 0; i < pos1; i++) bitp.add(v1[i], -1);
			for (int i = 0; i < pos2; i++) bitp.add(v2[i], -1);
			
			lop ^= 1, rop ^= 1;
			while (st.size()) st.pop();
			pos1 = sz1 - 1, pos2 = sz2 - 1, res = 0;
			for (int i = 1; i <= r - l + 1; i++)
			{
				if (rop ^ (i & 1))
				{
					if (pos1 < 0) break;
					st.push(make_pair(v1[pos1], 1));
					res += bitn.sum(v1[pos1]);
					res += bita.sum(n) - bita.sum(v1[pos1]);
					bitn.add(v1[pos1--], 1);
				}
				else
				{
					if (pos2 < 0) break;
					st.push(make_pair(v2[pos2], 0));
					res += bitn.sum(v2[pos2]);
					res += bita.sum(n) - bita.sum(v2[pos2]);
					bitn.add(v2[pos2--], 1);
				}
			}
			
			nx1 = pos1, nx2 = pos2, pos1 = pos2 = -1;
			if (nx1 == -1 && nx2 == -1) dp[c][1] = min(dp[c][1], dp[c - 1][1] + res);
			for (int i = 1; i <= r - l + 1; i++)
			{
				if (st.size() > (r - l + 1 - i))
				{
					pii tmp = st.top(); st.pop();
					if (tmp.second) nx1++;
					else nx2++;
					bitn.add(tmp.first, -1);
					res -= bitn.sum(tmp.first);
					res -= bita.sum(n) - bita.sum(tmp.first);
				}
				
				if (lop ^ (i & 1))
				{
					if (nx1 != nx2 + 1 || nx1 + nx2 + 2 != i) continue;
					if (pos2 < nx2)
					{
						pos2++;
						res += bita.sum(v2[pos2]);
						res += bitn.sum(v2[pos2]);
						res += bitp.sum(n) - bitp.sum(v2[pos2]);
						bitp.add(v2[pos2], 1);
					}
					if (pos1 < nx1)
					{
						pos1++;
						res += bita.sum(v1[pos1]);
						res += bitn.sum(v1[pos1]);
						res += bitp.sum(n) - bitp.sum(v1[pos1]);
						bitp.add(v1[pos1], 1);
					}
					dp[c][1] = min(dp[c][1], dp[c - 1][1] + res);
				}
				else
				{
					if (nx1 != nx2 || nx1 + nx2 + 2 != i) continue;
					if (pos1 < nx1)
					{
						pos1++;
						res += bita.sum(v1[pos1]);
						res += bitn.sum(v1[pos1]);
						res += bitp.sum(n) - bitp.sum(v1[pos1]);
						bitp.add(v1[pos1], 1);
					}
					if (pos2 < nx2)
					{
						pos2++;
						res += bita.sum(v2[pos2]);
						res += bitn.sum(v2[pos2]);
						res += bitp.sum(n) - bitp.sum(v2[pos2]);
						bitp.add(v2[pos2], 1);
					}
					dp[c][0] = min(dp[c][0], dp[c - 1][1] + res);
				}
			}
			for (int i = 0; i < pos1; i++) bitp.add(v1[i], -1);
			for (int i = 0; i < pos2; i++) bitp.add(v2[i], -1);
		}
		l = r + 1;
	}
	ll ans = min(dp[c][0], dp[c][1]);
	cout << (ans > 1e18 ? -1 : ans);
	return 0;
}