#include<bits/stdc++.h>

 #define pa pair<int,int>

 #define CLR(a,x) memset(a,x,sizeof(a))

 using namespace std;

 typedef long long ll;

 const int maxn=2e5+,logn=1e7;

 inline ll rd(){

     ll x=;char c=getchar();int neg=;

     while(c<''||c>''){if(c=='-') neg=-;c=getchar();}

     while(c>=''&&c<='') x=x*+c-'',c=getchar();

     return x*neg;

 }

 int siz[logn],ch[logn][],pct;

 int N;

 ll ans;

 void insert(int &p,int l,int r,int x){

     if(!p) p=++pct;

     siz[p]++;

     if(l==r) return;

     int m=l+r>>;

     if(x<=m) insert(ch[p][],l,m,x);

     else insert(ch[p][],m+,r,x);

 }

 ll merge(int &a,int b,int l,int r){

     if(!b) return ;

     if(!a){a=b;return ;}

     siz[a]+=siz[b];

     if(l==r) return ;

     ll re=1ll*siz[ch[a][]]*siz[ch[b][]];

     int m=l+r>>;

     re+=merge(ch[a][],ch[b][],l,m);

     re+=merge(ch[a][],ch[b][],m+,r);

     return re;

 }

 int dfs(){

     int x=rd();

     if(x!=){

         int rt=;

         insert(rt,,N,x);

         return rt;

     }

     int lc=dfs(),rc=dfs();

     ll sm=1ll*siz[lc]*siz[rc];

     if(siz[lc]>siz[rc]) swap(lc,rc);

     ll re=merge(lc,rc,,N);

     ans+=min(re,sm-re);

     return lc;

 }

 int main(){

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

     int i,j,k;

     N=rd();

     dfs();

     printf("%lld\n",ans);

     return ;

 }