#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>
#include <complex>
#include <cassert>

using namespace std;
using ll = long long;

int main(){

    ll N, ans=0, p, cnt=0;
    cin >> N;
    vector<ll> A(N);
    for (int i=0; i<N; i++) cin >> A[i];
    p = A[N-1];
    for (int i=N-2; i>=0; i--){
        if (A[i] != p) cnt++;
        else cnt=1;
        p = A[i];
        if (A[i] == 1) ans += cnt;
    }

    cout << ans << endl;

    return 0;
}