#include <bits/stdc++.h>
using namespace std;
#define foru(i,a,b) for(int i=(a); i<=(b); ++i)
#define ford(i,a,b) for(int i=(a); i>=(b); --i)
#define sz(a) (int)(a).size()
#define ll long long
#define _ << " " <<
template <class X, class Y> bool mini(X &x, Y y){return x>y?x=y,true:false;}
const int N=5e5+5;
int numTown,town[N];
void init(){
cin>>numTown;
foru(i,1,numTown) cin>>town[i];
}
vector<int> rar;
void compress(){
foru(i,1,numTown) rar.emplace_back(abs(town[i]));
rar.emplace_back(0);
sort(rar.begin(),rar.end());
rar.erase(unique(rar.begin(),rar.end()),rar.end());
foru(i,1,numTown){
int tmp=town[i]<0 ? -1 : 1;
town[i]=tmp * (lower_bound(rar.begin(),rar.end(),abs(town[i]))-rar.begin());
}
}
struct FenwickTree{
int f[N],tot;
vector<pair<int, int>> history;
void upd(int id, int val){
history.emplace_back(id,val);
tot+=val;
for(++id; id<N; id+=id&-id) f[id]+=val;
}
int getSmaller(int id){ /// or equal
int res=0;
for(++id; id>0; id-=id&-id) res+=f[id];
return res;
}
int getLarger(int id){
return tot-getSmaller(id);
}
void reset(){
for(auto [id,val]:history) upd(id,-val);
history.clear();
}
} fw1,fw2;
int smallLeft[N],smallRight[N];
void countSmall(){
foru(i,1,numTown){
fw1.upd(abs(town[i]),1);
smallLeft[i]=fw1.getSmaller(abs(town[i])-1);
}
fw1.reset();
ford(i,numTown,1){
fw1.upd(abs(town[i]),1);
smallRight[i]=fw1.getSmaller(abs(town[i])-1);
}
fw1.reset();
}
ll lastDP[2], DP[2], ansLeft[N], ansRight[N];
int id[N], signAtEven[N], useLeft[N][2], useRight[N][2];
void countAnswer(){
iota(id+1, id+1+numTown, 1);
sort(id+1, id+1+numTown, [](int x, int y){return abs(town[x]) > abs(town[y]);});
foru(i,1,numTown){
signAtEven[i]=(town[i]>0 && i%2==0) || (town[i]<0 && i%2==1);
/// signAtEven[i] = 1 -> > 0
}
DP[0]=0; DP[1]=1e18;
foru(i,1,numTown){
int l=i, r=i;
while(r<=numTown && abs(town[id[r]]) == abs(town[id[l]])) ++r;
--r;
if(abs(town[id[r]]) == 0){
break;
}
vector<int> sign[2];
foru(j,l,r) sign[signAtEven[id[j]]].emplace_back(id[j]);
foru(j,0,1) sort(sign[j].begin(),sign[j].end());
lastDP[0]=DP[0], lastDP[1]=DP[1];
DP[0]=DP[1]=1e18;
foru(leftP,0,1){
int rightP=(numTown+i+leftP)&1;
useLeft[0][0]=useLeft[0][1]=ansLeft[0]=0;
foru(j,1,r-l+1){
useLeft[j][0]=useLeft[j-1][0];
useLeft[j][1]=useLeft[j-1][1];
int curUse=(leftP+j)&1;
useLeft[j][curUse]++;
if(useLeft[j][0]>sz(sign[0]) || useLeft[j][1] > sz(sign[1])){
ansLeft[j] = 1e18;
} else{
ansLeft[j]=ansLeft[j-1];
int pos=sign[curUse][useLeft[j][curUse]-1];
ansLeft[j]+=fw1.getLarger(pos)+smallLeft[pos];
fw1.upd(pos, 1);
}
}
fw1.reset();
useRight[r-l+2][0]=useRight[r-l+2][1]=ansRight[r-l+2]=0;
ford(j,r-l+1,1){
useRight[j][0]=useRight[j+1][0];
useRight[j][1]=useRight[j+1][1];
int curUse=(rightP+(r-l+1-j))&1;
useRight[j][curUse]++;
if(useRight[j][0]>sz(sign[0]) || useRight[j][1] > sz(sign[1])){
ansRight[j] = 1e18;
} else{
ansRight[j]=ansRight[j+1];
int pos=sign[curUse][sz(sign[curUse])-useRight[j][curUse]];
ansRight[j]+=fw2.getSmaller(pos)+smallRight[pos];
fw2.upd(pos, 1);
}
}
ll cur=0;
foru(j,0,r-l+1){
if(j>=1){
int curUse=(leftP+j)&1;
if(useLeft[j][curUse] <= sz(sign[curUse])){
int pos = sign[curUse][useLeft[j][curUse]-1];
cur -= fw1.getLarger(pos);
fw2.upd(pos, -1);
cur += fw2.getSmaller(pos);
fw1.upd(pos, 1);
}
}
if(useLeft[j][0]+useRight[j+1][0]==sz(sign[0]) && useLeft[j][1]+useRight[j+1][1]==sz(sign[1])){
mini(DP[(leftP+j)&1], lastDP[leftP] + ansLeft[j]+ansRight[j+1]+cur);
}
}
fw1.reset(); fw2.reset();
}
i=r;
}
cout<<((min(DP[0],DP[1])==(ll)1e18)?-1:min(DP[0],DP[1]))<<'\n';
}
void solve(){
compress();
countSmall();
countAnswer();
}
int main(){
init();
solve();
}
