#include <iostream>
#include <vector>

typedef long long ll;
using namespace std;

template<typename H>
void print(H head) { cout << head << endl; }

template<typename H, typename... T>
void print(H&& head, T&&... tail){
  std::cout << head << " ", print(std::forward<T>(tail)...);
}


int main()
{
  ll N;
  cin >> N;

  std::vector<ll> va(N);
  for (auto& a : va) cin >> a;

  ll cnt = 0LL;
  ll ans = 0LL;
  for (ll i = 0; i < N; i++) {
    if (va[i] == 0) {
      ans += cnt * (cnt + 1) / 2;
      cnt = 0;
    } else {
      cnt++;
    }
  }
  ans += cnt * (cnt + 1) / 2;

  ll ans2 = N * (N+1) / 2 - ans;
  print(ans2);
  return 0;
}