public interface TRAI_25_X1 {

    /**
     * Second-smallest element of an array.
     *
     * The input array contains only valid integers (i.e., no null values).
     * Do not modify the input array.
     *
     * @param A Input array
     * @return the second-smallest element, or null if the array is empty or contains only one element.
     */
    Integer secondSmallest(Integer[] A);

}