vector<int> c1, c2;

void count_inv(int l, int r, ll &cnt) {
    if (l + 1 == r) return;
    int m = l + r >> 1;
    count_inv(l, m, cnt);
    count_inv(m, r, cnt);
    int i = l, j = m;
    for (int k = l; k < r; ++k) {
        if (i == m) {
            c2[k] = c1[j];
            ++j;
        } else if (j == r) {
            c2[k] = c1[i];
            cnt += j - m;
            ++i;
        } else if (c1[i] < c1[j]) {
            c2[k] = c1[i];
            cnt += j - m;
            ++i;
        } else {
            c2[k] = c1[j];
            ++j;
        }
    }
    for (int k = l; k < r; ++k) {
        c1[k] = c2[k];
    }
}

int main() {
    int n;
    cin >> n;
    vector<int> a(n);
    cin >> a;
    c1 = c2 = a;
    ll ans = 0;
    count_inv(0, n, ans);
    cout << ans << '\n';
    return 0;
}