#include <bits/stdc++.h>

using ll = long long;
   
using namespace std;

int main(){
    ll N;
    cin>>N;
    int a;
    ll cnt=0;
    ll sum=0;
    for(int i=0;i<N;i++){
        cin>>a;

        if(a){
            cnt++;
        }else{
          
            sum+=(cnt+1)*(cnt)/2;
            cnt=0;
        }
    }
    if(cnt){
        sum+=(cnt+1)*(cnt)/2;
    }
   // cout<<sum<<endl;
    
    ll ans=(N+1)*(N)/2-sum;
    cout<<ans<<endl;
    
}