#include <bits/stdc++.h>

using namespace std;
#define ll long long

int main()
{
    ll n;cin>>n;
    vector<int>a(n);
    for(int i=0;i<n;i++){
        cin>>a[i];
    }
    ll ans=0,res=(n*(n+1))/2;
    for(int i=0;i<n;i++){
        if(a[i]==1){
            ll j=i;
            ll c=0;
            while(j<n && a[j]==1){
                    c++;
            j++;

            }
            ans+=(c*(c+1))/2;
            i=j;
        }
    }
    cout<<res-ans;
    return 0;
}