#include<cstdio>

#include<cstdlib>

#include<iostream>

#include<string>

#include<set>

#include<algorithm>

#include<vector>

#include<queue>

#include<list>

#include<cmath>

#include<cstring>

#include<map>

#include<stack>

using namespace std;

#define INF 0x3f3f3f3f

#define maxn 2000005

#define ull unsigned long long

#define ll long long

#define hashmod 99999839

#define mod 9997

int n,x,y;

int ls[maxn],rs[maxn];//结点的左右儿子

int c[maxn],len;//结点代表的区间中有的个数

long long ans,s;

stack<int> st;

int newnode(){//返回一个新结点

    int p;

    if(st.empty()) p = len++;

    else p = st.top(),st.pop();

    ls[p] = rs[p] = ,c[p] = ;

    return p;

}

int bulid(int x){//建立叶子结点对应的树并返回根

    int root = newnode();//先申请一个新节点

    int l = ,r = n,mid,p = root;

    while(l < r){

        mid = (l + r) >> ;

        if(mid >= x) ls[p] = newnode(),p = ls[p],r = mid;

        else rs[p] = newnode(),p = rs[p],l = mid + ;

    }

    return root;

}

int merge(int p,int q){//合并以p,q为根的树,并返回新的根

    if(!p || !q) return p + q;

    s += (long long)c[rs[p]] * c[ls[q]];

    ls[p] = merge(ls[p],ls[q]);

    rs[p] = merge(rs[p],rs[q]);

    c[p] = c[ls[p]] + c[rs[p]];

    st.push(q);//可将合并了的q结点放入st中

    return p;

}

int solve(){

    scanf("%d",&x);

    if(x) return bulid(x);//对叶节点建立一颗线段树

    int p = solve(),q = solve();//建立其左右儿子

    ll t = c[p] * c[q];

    s = ,p = merge(p,q);//逆序对由非叶子结点产生

    if(s <= t / ) ans += s;

    else ans += t - s;

    return p;

}

void init(){

    while(!st.empty()) st.pop();

    len = ,ans = ;

}

int main(){

    freopen("a.in","r",stdin);

    freopen("b.out","w",stdout);

    scanf("%d",&n);

    init();

    solve();

    printf("%lld",ans);

    return ;

}