C++ :

#include<iostream>
#include<algorithm>
#include<cstring>
#include<ctime>
#include<cmath>
#include<string>
#include<cstdio>

typedef long long LL;

using namespace std;
typedef struct node{
    int num, size;
    LL cnt;
    struct node *lson, *rson, *next;
}*Node;

void build(Node rt)
{
    int v;
    scanf("%d", &v);
    rt->cnt = 0;
    rt->next = NULL;
    if(v != 0)
    {
        rt->num = v;
        rt->size = 1;
        rt->lson = rt->rson = NULL;
    }
    else
    {
        rt->num = 0;
        rt->lson = new node;
        build(rt->lson);
        rt->rson = new node;
        build(rt->rson);
        rt->next = rt->lson;
        rt->size = rt->lson->size + rt->rson->size;
    }
}
void Merge(Node rt)
{
    Node p = rt->lson, q = rt->rson, t1, t2, t3;
    if(q->size > p->size)
    {
        rt->lson = q; rt->rson = p;
        p = rt->lson; q = rt->rson;
    }
    LL lnum = 0, rnum = 0,
    l = rt->lson->size, r = rt->rson->size, c1 = 0, c2 = 0;

    rt->next = p; t1 = rt; t2 = t3 = NULL;

    //处理结点为０的情况
    if(!p->num) p = p->next, rt->next = p, t1 = rt;
    if(!q->num) q = q->next;

    //cout<<l<<"**"<<r<<endl;

    while(p && q)
    {
        if(p->num < q->num)
        {
            t1 = p;
            p = p->next;
            ++c1;
            lnum += r - c2;
        }
        else if(p->num > q->num)
        {
            t2 = q;
            while(q && p->num > q->num)
                ++c2, rnum += l - c1, t3 = q, q = q->next;
            t1->next = t2;
            t3->next = p;
            t1 = t3;
        }
        //不存在两个数相等的情况
//        else
//        {
//            int t = p->num, ll = 0, rr = 0;
//            while(p && p->num == t)
//            {
//                t1 = p;
//                p = p->next; ++ll; ++c1;
//            }
//            while(q && q->num == t)
//            {
//                t1->next = q;
//                t2 = q->next;
//                q->next = p;
//                q = t2;
//                t1 = t1->next; ++rr; ++c2;
//            }
//            lnum += ll * (r - c2);
//            rnum += rr * (l - c1);
//        }
    }
    if(!p) t1->next = q;
    rt->cnt = rt->lson->cnt + rt->rson->cnt + (lnum < rnum ? lnum : rnum);
    //cout<<rt->cnt<<"--->";
    //Node t = rt;
    //while(t) cout<<t->num<<" ", t = t->next;
    //cout<<endl;
}
void Travel(Node rt)
{
    if(rt->num) return;
    Travel(rt->lson);
    Travel(rt->rson);
    Merge(rt);
}
int main()
{
    //freopen("逆序对2.txt", "r", stdin);
    int n;
    scanf("%d", &n);
    Node root = new node;
    build(root);
    Travel(root);
    printf("%lld\n", root->cnt);
    return 0;
}