private static int getMiddle(int[] arr, int low, int high){
		int temp = arr[low];
		
		while(low < high){
			while(low < high && arr[high] >= temp){
				high--;
			}
			arr[low] = arr[high];
			while(low < high && arr[low] <= temp){
				low++;
			}
			arr[high] = arr[low];
		}
		arr[low] = temp;
		
		return low;
	}//a method of quick sort