#define _USE_MATH_DEFINES

#include <iostream>	//cin, cout
#include <vector>	//vector
#include <algorithm> //sort,min,max,count
#include <string>	//string,getline, to_string
#include <ios>		//fixed
#include <iomanip>	//setprecision
#include <utility> //swap, pair
#include <cstdlib>	//abs(int)
#include <cmath>	//sqrt,ceil,M_PI, pow, sin
#include <sstream>	//stringstream, getline
#include <numeric>	//gcd, accumlate
#include <deque>	//deque
#include <random>	//randam_device
#include <limits>	//numeric_limits

using namespace std;
constexpr long long int D_MOD = 1000000007;

int main() {

	int N;
	cin >> N;

	vector<int> A(N);
	for (int i = 0; i < N; i++) {
		cin >> A[i];
	}

	bool allone = true;

	long long int ans = 0;
	for (int i = 0; i < N; i++) {
		if (A[i] == 0) {
			ans += N - i;
			continue;
		}
		allone = true;
		for (int j = i + 1; j < N; j++) {
			if (A[j] == 0) {
				ans += N - j;
				allone = false;
				break;
			}
		}
		if (allone) {
			cout << ans << endl;
			return 0;
		}
	}

	cout << ans << endl;

	return 0;

}