// Template
#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <iomanip>
#include <tuple>
#include <utility>
#include <queue>
#include <set>
#include <map>
#include <array>
#include <cassert>
#include <cmath>
#define rep_override(x, y, z, name, ...) name
#define rep2(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep3(i, l, r) for (int i = (int)(l); i < (int)(r); ++i)
#define rep(...) rep_override(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define all(x) (x).begin(), (x).end()
using namespace std;
using ll = long long;
constexpr int inf = 1001001001;
constexpr ll infll = 3003003003003003003LL;
template <typename T>
inline bool chmin(T &x, const T &y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T> 
inline bool chmax(T &x, const T &y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &vec) {
    for (T &element : vec) is >> element;
    return is;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &vec) {
    for (int i = 0, vec_len = (int)vec.size(); i < vec_len; ++i) {
        os << vec[i] << (i + 1 == vec_len ? "" : " ");
    }
    return os;
}
struct IOSET {
    IOSET() {
        cin.tie(nullptr);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(10);
    }
} ioset;

// Main
int main() {
    int n;
    cin >> n;
    vector<int> a(n);
    cin >> a;
    
    /*
    bool all1 = true;
    rep(i, n) if (a[i] == 0) all1 = false;
    if (all1) {
        cout << "0\n";
        return 0;
    }
    */
    
    a.insert(a.begin(), 0);
    a.push_back(0);
    
    int memo = 0;
    ll ans = (ll) n * (n + 1) / 2;
    rep(i, 1, n + 2) {
        if (a[i] == 0) {
            ll d = i - memo - 1;
            ans -= d * (d + 1) / 2;
            memo = i;
        }
    }
    
    cout << ans << '\n';
}