#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    ll n; cin >> n;
    ll cnt = 0;
    ll ans = (n*(n+1))/2;
    for(int i = 0; i < n; i++){
        int a; cin >> a;
        if(a == 1){
            cnt++;
        }else{
            ans -= (cnt*(cnt+1))/2;
            cnt = 0;
        }
    }
    ans -= (cnt*(cnt+1))/2;
    cout << ans << endl;
}