/*
 * Return the index of element x within array A if present,
 * and return -1 if not found
 */
static public int BinarySearch (int [] A, int x)
{
    int left = 0;
    int right = A.length - 1;
    while (left <= right)
    {
        int mid = (left + right) / 2;
    
	if (A[mid] == x) 
	    return mid;
    
        else if (A[mid] < x)
	    left = mid + 1;

        else right = mid - 1;
    }
    return -1;
}