#include <iostream>
#include <stdio.h>
#include <vector>
#include <map>
#include <stack>
#include <cstring>
#include <set>
#include <utility>
#include <iostream>
#include <iomanip>
#include <list>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cctype>
//#include <boost/multiprecision/cpp_int.hpp>
#include <unordered_set>
#include <bitset>
#include <cassert>
#include <numeric>
#include <complex>
#define FOR(i,a,b) for (ll i=(a);i<(ll)(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define SUM(v) accumulate(ALL(v),0ll)
using ll = long long;
const ll INF=1e18;
const ll eps=1;
const double pi=3.14159265359;
const ll mod=10000000000+7;
using I32 = int32_t;
using I64 = int64_t;
using namespace std;
//Union Find テンプレ
struct UnionFind {
  vector<int> par , siz;
  UnionFind(int n) : par(n,-1) , siz(n,1) { }
  int root(int x) {
    if(par[x] == -1) return x;
    else return par[x] = root(par[x]);
  }
  bool issame(int x, int y) {
    return root(x) == root(y);
  }
  bool unite(int x, int y) {
    x = root(x) ; y = root(y);
    if(x == y) return false;
    if(siz[x] < siz[y]) swap(x,y);
    par[y] = x;
    siz[x] += siz[y];
    return true;
  }
  int size(int x) {
    return siz[root(x)];
  }
};
typedef pair<int,int> P;
bool prime(ll k)
{
  if(k==1)return false;
  if(k%2==0)return false;
  for(ll i=3;i*i<=k;i+=2)
  {
    if(k%i==0)return false;
  }
  return true;
}
ll memo[10000001];
int main()
{
  ll n;
  cin>>n;
  vector<ll> a(n);
  REP(i,n)cin>>a[i];
  ll one=0;
  ll cnt=0;
  bool ok=false;
  REP(i,n)
  {
    if(a[i]==1)
    {
      ok=true;
      one++;
    }
    else if(a[i]==0&&ok==true)
    {
      ok=false;
      cnt+=one*(one+1)/2;
      one=0;
    }
  }
  cnt+=one*(one+1)/2;
  ll ans=n*(n+1)/2-cnt;
  cout<<ans<<endl;
  return 0;
}