int upperBound(const vector<int> &a, int x) {
    int l = 0, r = (int)a.size();
    while (l < r) {
        int mid = l + (r - l) / 2;
        if (__________________) {
            l = mid + 1;
        } else {
            r = mid;
        }
    }
    return l;
}