#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<cstdlib>
#include<vector>
#include<queue>
#include<map>
using namespace std;
#define re int
#define ll long long
inline int read(){
	int x=0,ff=1;char c=getchar();
	while(c<'0'||c>'9'){if(c=='-')ff=-1;c=getchar();}
	while(c>='0'&&c<='9'){x=(x<<1)+(x<<3)+(c^'0');c=getchar();}
	return x*ff; 
}
const ll inf=1e18;
int n,a[500005],c[500005],N;
vector<int> d[500005];
ll f[2],g[2];
inline int fs(int x){return x&-x;}
int s[500005];
inline void add(int x,int y){while(x<=n)s[x]+=y,x+=fs(x);}
inline int find(int x){int y=0;while(x)y+=s[x],x-=fs(x);return y;}
int p[500005],q[500005],vl[500005];
bool qwq[500005];
int _s[500005],kk[500005];
inline void _add(int x,int y){while(x<=n)_s[x]+=y,x+=fs(x);}
inline int _find(int x){int y=0;while(x)y+=_s[x],x-=fs(x);return y;}
void solve(int m,bool fl){
	g[0]=f[0];g[1]=f[1];
	f[0]=f[1]=inf;int x,t,Q=find(n);ll y;
	for(re i=1;i<=m;i++)qwq[i]=(q[i]>0)^(p[i]&1),vl[i]=find(p[i]);
	for(re l=0;l<2;l++){y=0;
		if(g[l]==inf)continue;
		x=l^1;vector<int> V[2],U,K;
		int v[2],u[2];v[0]=v[1]=0;
		for(re i=1;i<=m;i++)V[qwq[i]].emplace_back(i);
		while(23333){
			if(v[x]==V[x].size())break;
			U.emplace_back(V[x][v[x]]);v[x]++;
			x^=1;
		}
		u[0]=V[0].size()-1;u[1]=V[1].size()-1;
		t=x;x=l^fl^1;
		while(23333){
			if(u[x]<v[x])break;
			K.emplace_back(V[x][u[x]]);u[x]--;
			x^=1;
		}
		if(K.size()+U.size()!=V[0].size()+V[1].size())continue;
		int now=0;
		for(re i:U)y+=(kk[now++]=_find(n)-_find(p[i])+vl[i]),_add(p[i],1);
		for(re i:K)y+=(kk[now++]=_find(n)-_find(p[i])+Q-vl[i]),_add(p[i],1);
		for(re i:K)_add(p[i],-1);
		f[t^1]=min(f[t^1],y+g[l]);
		for(re i=U.size()-1;i>=0;i--){
			if(qwq[U[i]]!=x){
				if(i>0){
					i--; _add(p[U[i]],-1);_add(p[U[i+1]],-1);
					y-=kk[i];y+=_find(n)-_find(p[U[i]])+Q-vl[U[i]];
					x^=1;t^=1;i++;//f[t^1]=min(f[t^1],y+g[l]+((p[U[i-1]]>p[U[i]])?-1:1));
					y-=kk[i];y+=_find(n)-_find(p[U[i]])+Q-vl[U[i]];
					if(p[U[i-1]]<p[U[i]])y++;
					x^=1;t^=1;i--;f[t^1]=min(f[t^1],y+g[l]);
				}
				else _add(p[U[i]],-1);
				continue;
			}_add(p[U[i]],-1);
			y-=kk[i];y+=_find(n)-_find(p[U[i]])+Q-vl[U[i]];
			x^=1;t^=1;f[t^1]=min(f[t^1],y+g[l]);
		}
	}
}
int main(){
	n=read();
	for(re i=1;i<=n;i++)a[i]=read(),c[++N]=abs(a[i]);
	sort(c+1,c+N+1);N=unique(c+1,c+N+1)-c-1;
	for(re i=1;i<=n;i++){
		d[lower_bound(c+1,c+N+1,abs(a[i]))-c].emplace_back(i);
		add(i,1);
	}
	bool fl=n&1;int x;
	f[0]=0;f[1]=inf;
	for(re i=N;i;i--){x=0;
		if(c[i]==0)break;
		for(re j:d[i]){
			add(j,-1);p[++x]=j;q[x]=a[j];
		}
		solve(x,fl);fl^=(x&1);
		//cerr<<f[0]<<" "<<f[1]<<endl;
	}
	if(min(f[0],f[1])>=inf)puts("-1");
	else cout<<min(f[0],f[1]);
	return 0;
}