/**
*    author:  shu8Cream
*    created: 15.05.2021 13:04:09
**/

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i=0; i<(n); i++)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
using ll = long long;
using P = pair<ll,ll>;
using vi = vector<ll>;
using vvi = vector<vi>;

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll n; cin >> n;
    vi a(n); rep(i,n) cin >> a[i];
    ll ans = 0, cnt = 0;
    rep(i,n){
        if(a[i]) cnt++;
        else{
            ans += (cnt+1)*cnt/2;
            cnt = 0;
        }
    }
    ans += (cnt+1)*cnt/2;
    cout << (n+1)*n/2-ans << endl;
}