#include<bits/stdc++.h>
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T>
bool chmax(T &val, T nv) {
    return val < nv ? (val = nv, true) : false;
}
template<class T>
bool chmin(T &val, T nv) {
    return nv < val ? (val = nv, true) : false;
}
using namespace std;
using ll = long long;
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void debug(auto L, auto R) { while (L < R) cerr << *L << " \n"[L+1==R], ++L; }
void kout(){ cerr << endl; }
template<class T1, class ...T2> void kout(T1 a, T2 ...e) { cerr << a << ' ', kout(e...); }
#else
#define DE(...) 0
#define debug(...) 0
#endif
// What I should check
// 1. overflow
// 2. corner cases
// Enjoy the problem instead of hurrying to AC
// Good luck !
const int MAX_N = 200010;

#include <bits/extc++.h>
using namespace __gnu_pbds;

using bst = tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>;



ll solve(bst &pa) {
    bst now;
    int p;
    cin >> p;
    // branch
    ll res = 0;
    if (p == 0) {
        res += solve(now);
        res += solve(now);
    }
    // leaf
    else {
        now.insert(p);
    }
    if (pa.empty()) {
        pa.swap(now);
    }
    else {
        if (now.size() > pa.size()) pa.swap(now);
        ll f = 0, b = 0;
        for (int u : now) {
            int k = pa.order_of_key(u);
            f += k, b += pa.size() - k;
        }
        res += min(f, b);
        for (int u : now)
            pa.insert(u);
    }
    return res;
}
int32_t main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    int n;
    cin >> n;
    bst _;
    cout << solve(_) << '\n';
}