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