How use running-total for hierarchical dimension

[technol]

 Hi, I need use correctly the function running-total i have this:

                        amount   running-total
Country1  city1  200        200
               city2  100        300
               city3   50         350
country2  city1   100        100
               city2   20          320   ::)  (in this case, i should have 120, not 320)

In my instruction running-total:
running-total(([amount]) for ([city]))

How can i get control-rupture for city and country ???