#include<bits/stdc++.h>

#define LL long long

using namespace std;

const int N = 2e5 + 5;

int n;
LL ans, u, v;
// 权值线段树
struct Node{
    int ls, rs;
    int size;
}tr[22 * N];//N * logN的空间
int cnt;

void insert(int &now, int l, int r, int val){

    tr[now = ++ cnt].size ++ ;
    if(l == r) return;

    int mid = l + r >> 1;
    if(val <= mid) insert(tr[now].ls, l, mid, val);
    else insert(tr[now].rs, mid + 1, r, val);
    // 不用 pushup
}

// 类似归并排序 求逆序对
int merge(int p, int q, int l, int r){ 
    if(!q || !p) return p + q;
    if(l == r){
        tr[p].size += tr[q].size;
        return p; // 删除 q
    }
    u += (LL)tr[tr[p].rs].size*tr[tr[q].ls].size; //交换前 
    v += (LL)tr[tr[p].ls].size*tr[tr[q].rs].size; //交换后 
    int mid = l + r >> 1;
    tr[p].ls = merge(tr[p].ls, tr[q].ls, l, mid);
    tr[p].rs = merge(tr[p].rs, tr[q].rs, mid + 1, r);
    tr[p].size = tr[tr[p].ls].size + tr[tr[p].rs].size; 
    return p;
}

int dfs(){

    int root, val;
    scanf("%d", &val);

    if(!val){ 
        int ls = dfs(), rs = dfs();
        u = 0; v = 0; //清零 // u 代表不换  v 代表换
        root = merge(ls, rs, 1, n);
        ans += min(u, v);
    }
    else insert(root, 1, n, val);
    return root;
}

int main(){

    scanf("%d", &n);

    dfs(); // 递归读入
    printf("%lld", ans);

    return 0;
}