#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef modint1000000007 mint;
typedef pair<ll,ll> P;
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define rrep(i,a,b) for(ll i=a;i>=b;i--)
const ll inf=1e18;
ll n;
ll a[200005];
vector<ll> z;
ll ans;
int main(void){
    cin.tie(0);
    ios::sync_with_stdio(0);
    cin>>n;
    ans=n*(n+1)/2;
    z.push_back(-1);
    rep(i,0,n){
        cin>>a[i];
        if(a[i]==0){
            z.push_back(i);
        }
    }
    z.push_back(n);
    rep(i,1,z.size()){
        ans-=(z[i]-z[i-1]-1)*(z[i]-z[i-1])/2;
    }
    cout<<ans<<endl;
}