int rank(int key, int[] a) {
        int low = 0;
        int high = a.length - 1;
        while (low <= high) {
            int mid = low + (high - low) / 2;
            if (key < a[mid]) { high = mid - 1; } else if (key > a[mid]) { low = mid + 1; } else { return mid; } } return -1; }