#define _GLIBCXX_DEBUG
#define ll long long
#include <bits/stdc++.h>
using namespace std;

int main() {
  int N; cin >> N;
  vector<ll> S(200002);
  for(int i = 1; i < 200000; i++){
    S[i] = S[i-1] + i;
  }
  long long ans = S[N];
  int len = 0;
  for(int i = 0; i < N; i++){
    int A; cin >> A;
    if(A == 1) len++;
    else{
      ans -= S[len];
      len = 0;
    }
    if(i+1 == N){
      ans -= S[len];
    }
  }
  cout << ans << endl;
}