public void removeVerticalSeam(int[] a) {
        if (!validSeam(a, width() - 1)) {
            throw new IllegalArgumentException("Input seam is not valid");
        }
        if (a.length != height()) {
            throw new IllegalArgumentException(
                    "Input seam is not equal to picture height");
        }
        if (width() <= 1) {
            throw new IllegalArgumentException("Picture width <= 1");
        }
        if (transposed) {
            transpose();
            transposed = false;
        }
        removeSeam(a);
    }