#include "bits/stdc++.h"
//#include "atcoder/all"
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
//const bool debug = false;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	long long n; cin >> n;
	long long ans = n * (n + 1) / 2;
	vector<int>a(n);
	rep(i, n)cin >> a[i];
	for (int i = 0; i < n; ++i) {
		if (0 == a[i])continue;
		long long j = i;
		for (; j < n; ++j) {
			if (0 == a[j]) break;
		}
		//cout << i << " " << j << endl;
		ans -= (j - i) *(j - i + 1) / 2;
		i = j;
	}
	cout << ans << endl;
	return 0;
}