#include <algorithm>
#include <array>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <optional>
#include <queue>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

int main() {
    int32_t n;
    cin >> n;
    vector<bool> as(n);
    for (auto &&a : as) {
        int32_t x;
        cin >> x;
        a = x == 1;
    }
    vector<int32_t> rl;
    int32_t cnt = 0;
    for (auto a : as) {
        if (a)
            ++cnt;
        else {
            rl.push_back(cnt);
            cnt = 0;
        }
    }
    rl.push_back(cnt);
    for (auto &&x : rl) {
        ++x;
    }
    int64_t ans = 0, sum = 0;
    for (auto x : rl) {
        ans += x * sum;
        sum += x;
    }
    cout << ans << endl;
    return 0;
}