public void merge(int low,int mid,int high)
	{
		int[] helper = new int[a.length];
		for(int i=low;i<=high;i++)
		{
			helper[i] = a[i];
		}
		
		int i= low;
		int j = mid+1;
		int k = low;
		
		while(i <= mid && j <= high)
		{
			if(helper[i] <= helper[j])
			{
				a[k] = helper[i]; 
				i++;
				k++;
			}
			else
			{
				a[k] = helper[j];
				j++;
				k++;
			}
		}
		
		while(i <= mid)
		{
			a[k] = helper[i];
			i++;
			k++;
		}
	}