need help with cracking sha1 hash

[nhatcto]

hello to all
i got some sha1 hash
show type : sha1($salt.sha1($salt.sha1($pass)))


and i am using hashcat gui of hashkiller
but i can not find the type sha1($salt.sha1($salt.sha1($pass))) on that tool

pls tell me how i can crack list hash of that type on CPU only