#include <bits/stdc++.h>
#define FOR(i, n, m) for(long long i = (n); i < (long long)(m); i++)
#define REP(i, n) FOR(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define pb push_back
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<ll, ll>;
constexpr ll inf = 1000000000;
constexpr ll mod = 998244353;
constexpr ld eps = 1e-6;

template <typename T1, typename T2>
ostream &operator<<(ostream &os, pair<T1, T2> p) {
    os << to_string(p.first) << " " << to_string(p.second);
    return os;
}
template <typename T> ostream &operator<<(ostream &os, vector<T> &v) {
    REP(i, v.size()) {
        if(i)
            os << " ";
        os << v[i];
    }
    return os;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    vector<int> a(n);
    REP(i, n) cin >> a[i];
    ll ans = 0;
    vector<vector<int>> lasts(2, vector<int>(2, n - 1));
    for(int i = n - 1; i >= 0; i--) {
        lasts[i % 2][a[i]] = i;
        ans += min(lasts[i % 2][0], lasts[!(i % 2)][1]) - i;
    }
    cout << ans << endl;
    return 0;
}