#ifdef t9unkubj
#include"debug.cpp"
//#include"template_no_debug.h"
#else 
#define dbg(...) 199958
#endif

#undef _GLIBCXX_DEBUG
#pragma GCC optimize("O3")
using namespace std;
#include<bits/stdc++.h>
using ll=long long;
using ull=unsigned long long;
template<class T>using vc=vector<T>;
template<class T>using vvc=vc<vc<T>>;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define REP(i,j,n) for(ll i=(j);i<(ll)(n);i++)
#define DREP(i,n,m) for(ll i=(n);i>=(m);i--)
#define drep(i,n) for(ll i=((n)-1);i>=0;i--)
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
template<class T,class F>
bool chmin(T &x, F y){
    if(x>y){
        x=y;
        return true;
    }
    return false;
}
template<class T, class F>
bool chmax(T &x, F y){
    if(x<y){
        x=y;
        return true;
    }
    return false;
}
double pass_time=0;
void solve(){
    int n;
    cin>>n;
    vc<int>a(n);
    rep(i,n)cin>>a[i];
    vc<int>ans(n);
    vc<int>rev(n);
    drep(i,n-1){
        {
            if(a[i]==0){}
            else{
                if(a[i+1]==0){
                    ans[i]=rev[i+1]+1;
                }else ans[i]=1;
            }
        }
        {
            if(a[i]==1){}
            else{
                if(a[i+1]==1){
                    rev[i]=ans[i+1]+1;
                }else rev[i]=1;
            }
        }
    }
    cout<<accumulate(all(ans),0ll)<<"\n";
}
signed main(){
    cin.tie(0)->sync_with_stdio(0);
    pass_time=clock();
    int t=1;
    //cin>>t;
    while(t--)solve();
    pass_time=clock()-pass_time;
    dbg(pass_time/CLOCKS_PER_SEC);
}