Google Sheets – How to Do Sum(Max(…))

Here is my raw data:

   Site    IP        Visits    Age (in hours)
1  uu.com  1.2.3.4   10        3                  
2  vv.com  2.9.7.5   2         4
3  kk.com  2.9.7.5   8         24
4  uu.com  1.2.3.4   12        24                  
5  vv.com  2.9.7.5   10        24
6  kk.com  2.9.7.5   8         48

I have build a pivot table like this in Google spreadsheet:

   Col. A    Col. B   MAX of Visits   MAX of Age
1  1.2.3.4   uu.com   12              24    
2  2.9.7.5   kk.com   8               48
3            vv.com   10              24

When I ask Google Spreadsheet to give the totals, I get the following result:

   Col. A             Col. B   MAX of Visits   MAX of Age
1  1.2.3.4            uu.com   12              24    
2  Total for 1.2.3.4           12              24
3  2.9.7.5            kk.com   8               48
4                     vv.com   10              24
5  Total for 2.9.7.5           10              48

This is not what I'm expecting because I want the SUM('Max of visits') as total.
Clearly, this is the final pivot table I want:

   Col. A             Col. B   MAX of Visits   MAX of Age
1  1.2.3.4            uu.com   12              24    
2  Total for 1.2.3.4           12              24
3  2.9.7.5            kk.com   8               48
4                     vv.com   10              24
5  Total for 2.9.7.5           18              48

Notice on line 5 , column 'Max of Visits', I want 18 and not 10 as Google Spreadsheet gives me.

How can I acheive that ?