#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define I64 long long
using namespace std;
using namespace __gnu_pbds;
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = (int) 2E5;
int n;
int e[N * 2 - 1][2];
int t;
ordered_set<int> s[N * 2 - 1];
int build(int u) {
int p = t;
t = t + 1;
int x;
cin >> x;
if (x == 0) {
e[u][0] = build(t);
e[u][1] = build(t);
} else {
s[u].insert(x);
}
return p;
}
I64 x;
void DFS(int u) {
if (e[u][0] >= 0) {
int v[2];
v[0] = e[u][0];
v[1] = e[u][1];
DFS(v[0]);
DFS(v[1]);
if (s[v[0]].size() < s[v[1]].size()) {
s[v[0]].swap(s[v[1]]);
}
I64 a = 0, b = 0;
for (auto x : s[v[1]]) {
a = a + (int) s[v[0]].order_of_key(x);
b = b + (int) (s[v[0]].size()) - (int) s[v[0]].order_of_key(x);
}
s[u].swap(s[v[0]]);
x = x + min(a, b);
for (auto x : s[v[1]]) {
s[u].insert(x);
}
}
}
void solve() {
cin >> n;
n = n * 2 - 1;
for (int i = 0; i < n; i++) {
e[i][0] = 0 - 1;
e[i][1] = 0 - 1;
}
build(0);
DFS(0);
cout << x << "\n";
}
int main() {
ios::sync_with_stdio(0);
cin.tie(nullptr);
solve();
return 0;
}
