how to seprate n times square bracket

hi
my artist field is Alishmas/Mehdi Jahani/Mehdi Jahani/Mehdi Jahani/Baranoosh or Alishmas/Mehdi Jahani/Mehdi Jahani/Mehdi Jahani or ... and it is not clear how many "/" exist on field!
and i want change that to "Alishmas Ft Mehdi Jahani"
please help me what should i do?

Use a regular expression:

$regexp('Alishmas/Mehdi Jahani/Mehdi Jahani/Mehdi Jahani/Baranoosh',(.?)/(.?)/.*,$1 ft. $2)

perhaps you replace the "'Alishmas/Mehdi Jahani/Mehdi Jahani/Mehdi Jahani/Baranoosh'" part with %artist%

$regexp(%artist%,(.?)/(.?)/.*,$1 ft. $2)