#include<bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
#define double long double
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
//typedef long double ld;
typedef complex<double> Complex;
const ll INF=1e9+7;
const ll MOD=INF;
const ll inf=INF*INF;
const ll mod=MOD;
const ll MAX=200010;



signed main(){
    ll n;cin>>n;
    vector<ll>a(n);
    rep(i,n)cin>>a[i];
    a.pb(0);
    ll cnt=0;
    ll ans=n*(n+1)/2;
    rep(i,n+1){
        if(a[i]==0){
            ans-=cnt*(cnt+1)/2;
            cnt=0;
        }else{
            cnt++;
        }
    }
    cout<<ans<<endl;
}