#pragma GCC optimize ("O2")
#pragma GCC target ("avx")
#include<bits/stdc++.h>
//#include<atcoder/all>
//using namespace atcoder;

using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	int N;
	cin >> N;

	ll kotae = (ll)N * (N + 1) / 2;

	ll kazu = 0;
	rep(i, N) {
		int a;
		cin >> a;
		if (a == 0) {
			kotae -= kazu * (kazu + 1) / 2;
			kazu = 0;
		}
		else kazu++;
	}
	co(kotae - kazu * (kazu + 1) / 2);

	Would you please return 0;
}