macro - search within a cell and edit the text string

Hello, I have this problem:
I need to search the fourth occurence of the character / within each cell of a database of web links and delete all characters that come after it.

the links look like this:
http://www.parfums.cz/banana-republi...toaletni-voda/
http://www.parfums.cz/benetton/benet...toaletni-voda/
http://www.parfums.cz/bugatti/bugatt...toaletni-voda/
http://www.parfums.cz/dsquared2/dsqu...toaletni-voda/
http://www.parfums.cz/la-perla/la-pe...toaletni-voda/
http://www.parfums.cz/mauboussin/mau...femovana-voda/
http://www.parfums.cz/naomi-campbell...toaletni-voda/

i need them to look like this:
http://www.parfums.cz/banana-republic/
http://www.parfums.cz/benetton/
http://www.parfums.cz/bugatti/
http://www.parfums.cz/dsquared2/
http://www.parfums.cz/la-perla/
http://www.parfums.cz/mauboussin/
http://www.parfums.cz/naomi-campbell/

Thank you in advance for your help
Filip

well, I solved it without macros with this formula:

=LEFT(C56;FIND("/";C56;30))
where C56 is a cell with original link and 30 is a number approximately between the 3rd and 4th char /

But it creates a new table with the final links. I would like to have it on the same place, where the original links were and have a mean that would be lenght-proof
(there is also domain http://aoro.ro/ which is much shorter and some much longer as well)