#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using Graph = vector<vector<int> >;

#define rep(i, a, b) for(int i = a; i < b; i++)
#define rrep(i, a, b) for(int i = a; i >= b; i--)
#define fore(i, a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()

const int INFI = 1 << 29;
const ll INFL = 1LL << 59;

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

    int n; cin >> n;
    vector<int> A(n);
    fore (i, A) cin >> i;

    bool swtch = true;
    ll tmp = 0, ans = 0;
    rep(i, 0, n) {
        if (A[i] == 1 and swtch == true) {
            tmp++;
            swtch = false;
        }
        else if (A[i] == 0 and swtch == false) {
            tmp++;
            swtch = true;
        }
        else {
            ans += tmp;
            tmp;
            ll tmp2 = (tmp / 2);
            ans += tmp2 * (tmp2 + 1) / 2;
            if (A[i] == 1) tmp = 0, swtch = false;
            else tmp = 0, swtch = true;
        }
    }
    ans += tmp;
    tmp;
    ll tmp2 = (tmp / 2);
    ans += tmp2 * (tmp2 + 1) / 2;

    cout << ans << endl;
}