public int FindPosition(int num, int[] arr)                {                    int left = 0;                    int right = arr.Length - 1;                                    while (left < right - 1)                    {                        if (arr[left] == num)                        {                            return left;                        }                        if (arr[right] == num)                        {                            return right;                        }                                        int middle = (left + right) / 2;                        if (num == arr[middle])                        {                            return middle;                        }                        else if (num < arr[middle])                        {                            right = middle;                        }                        else                        {                            left = middle;                        }                                    }                    return -1;                }