// Source: https://oj.uz/problem/view/POI11_rot
// State: Writing...
#include <ext/pb_ds/assoc_container.hpp>
#include <bits/stdc++.h>
#include <ios>
using namespace std;
using namespace __gnu_pbds;
//#define int long long
template <class T>
using Tree =
tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
long long ans = 0;
Tree<int> s[200001];
int timedfs = 1;
void solve(int id){
int x;
// Tree<int> s1,s2;
cin >> x;
if (x != 0){
s[id].insert(x);
return;
}
int s1 = ++timedfs;
solve(s1);
int s2 = ++timedfs;
solve(s2);
if (s[s1].size() < s[s2].size()) swap(s[s1], s[s2]);
swap(s[s1],s[id]);
//auto i1 = s1.begin(), i2 = s2.begin();
long long nghich = 0;
for (int v : s[s2])
nghich = nghich + s[id].order_of_key(v);
ans = ans + min((long long)nghich,(long long)s[id].size()*(long long)s[s2].size() - nghich);
//cout << ans << endl;
for (int v : s[s2]){
s[id].insert(v);
}
s[s1].clear();
s[s2].clear();
//swap(s[id],s[s1]);
return;
}
int32_t main() {
ios_base::sync_with_stdio(NULL);
cin.tie(NULL);cout.tie(NULL);
int n;
cin >> n;
solve(0);
cout << ans;
}
