#include<bits/stdc++.h>
using namespace std;
vector<long long> idk(500001);
vector<long long> lol(500001);
vector<long long> no(500001);
vector<pair<long long,long long>> roll(0);
void reset() {
for(int i = (int)roll.size()-1; i >= 0; i--) {
lol[roll[i].second] = roll[i].first;
}
roll.clear();
}
void upd2(long long a, long long x) {
while(a < lol.size()) {
roll.push_back({lol[a],a});
lol[a]+=x;
a+=(a&(-a));
}
}
long long calc2(long long a) {
long long c = 0,sb = 0;
for(long long i = 19; i >= 0; i--) {
if(c+(1 << i) <= a) {
c+=(1 << i);
sb+=lol[c];
}
}
return sb;
}
pair<long long, long long> dude(long long n, vector<long long>& haha, vector<long long>& bruh, long long q) {
long long ans1 = LLONG_MAX,ans2 = LLONG_MAX;
reset();
long long br = n;
long long s = haha.size()+bruh.size();
long long y1 = 0,y2 = 0,z1 = (long long)haha.size()-1,z2 = (long long)bruh.size()-1;
vector<long long> sb1(s+1,-1);
vector<long long> sb2(s+1,-1);
sb1[0] = 0;
sb2[0] = 0;
vector<pair<long long,long long>> idk1(1,{0,0});
vector<pair<long long,long long>> idk2(1,{0,0});
for(long long i = 1; i <= s; i++) {
long long a;
if(i%2) {
if(y1 >= haha.size()) {
break;
}
a = haha[y1];
y1++;
}
else {
if(y2 >= bruh.size()) {
break;
}
a = bruh[y2];
y2++;
}
upd2(a,-1);
sb1[i] = sb1[i-1]+calc2(a)+a;
idk1.push_back({y1,y2});
}
reset();
for(int x: haha) {
br--;
upd2(x,1);
}
for(int x: bruh) {
br--;
upd2(x,1);
}
for(long long i = 1; i <= s; i++) {
long long a;
if((i+n)%2) {
if(z1 < 0) {
break;
}
a = haha[z1];
z1--;
}
else {
if(z2 < 0) {
break;
}
a = bruh[z2];
z2--;
}
sb2[i] = sb2[i-1]+calc2(a)-a+br;
upd2(a,1);
idk2.push_back({(long long)haha.size()-z1-1,(long long)bruh.size()-z2-1});
}
while(idk1.size() <= s+1) {
idk1.push_back({-1,-1});
}
while(idk2.size() <= s+1) {
idk2.push_back({-1,-1});
}
for(long long i = 0; i <= s; i++) {
if(sb1[i] != -1 && sb2[s-i] != -1) {
if(idk1[i].first+idk2[s-i].first == haha.size() && idk1[i].second+idk2[s-i].second == bruh.size()) {
if(i%2 == 0) {
ans1 = min(ans1,sb1[i]+sb2[s-i]);
}
else {
ans2 = min(ans2,sb1[i]+sb2[s-i]);
}
}
}
}
return {ans1,ans2};
}
void upd(long long a, long long x) {
while(a < idk.size()) {
idk[a]+=x;
a+=(a&(-a));
}
}
long long calc(long long a) {
long long c = 0,sb = 0;
for(long long i = 19; i >= 0; i--) {
if(c+(1 << i) <= a) {
c+=(1 << i);
sb+=idk[c];
}
}
return sb;
}
int main()
{
ios_base::sync_with_stdio(NULL);
cin.tie(NULL);
cout.tie(NULL);
long long n,ans = 0;
cin >> n;
vector<long long> haha(n+1);
vector<pair<long long,long long>> wut(0);
vector<long long> dp0(n+1,LLONG_MAX);
vector<long long> dp1(n+1,LLONG_MAX);
dp0[0] = 0;
for(long long i = 1; i <= n; i++) {
cin >> haha[i];
no[i] = haha[i];
wut.push_back({-abs(haha[i]),i});
}
sort(wut.begin(),wut.end());
for(int i = 0; i < n; i++) {
wut[i] = {-wut[i].first,wut[i].second};
}
for(long long i = 1; i <= n; i++) {
upd(i,1);
}
long long y = 0;
while(y < n) {
long long a = wut[y].first;
if(a == 0) {
dp0[n] = dp0[y];
dp1[n] = dp1[y];
}
vector<long long> banana1(0);
vector<long long> banana2(0);
long long r = n-1;
for(long long i = y; i < n; i++) {
if(abs(wut[i].first) != a) {
r = i-1;
break;
}
}
for(long long i = y; i <= r; i++) {
long long c = 0;
if(haha[wut[i].second] > 0) {
c = 1;
}
if((c+wut[i].second)%2) {
banana1.push_back(calc(wut[i].second));
}
else {
banana2.push_back(calc(wut[i].second));
}
}
pair<long long,long long> x = dude(n-y,banana1,banana2,a);
if(dp0[y] != LLONG_MAX) {
if(x.first != LLONG_MAX) {
dp0[r+1] = min(dp0[r+1],dp0[y]+x.first);
}
if(x.second != LLONG_MAX) {
dp1[r+1] = min(dp1[r+1],dp0[y]+x.second);
}
}
x = dude(n-y,banana2,banana1,a);
if(dp1[y] != LLONG_MAX) {
if(x.first != LLONG_MAX) {
dp1[r+1] = min(dp1[r+1],dp1[y]+x.first);
}
if(x.second != LLONG_MAX) {
dp0[r+1] = min(dp0[r+1],dp1[y]+x.second);
}
}
for(int i = y; i <= r; i++) {
upd(wut[i].second,-1);
}
y = r+1;
}
ans = min(dp0[n],dp1[n]);
if(ans == LLONG_MAX) {
cout << -1;
}
else {
cout << ans;
}
return 0;
}
