SSRS 2008 R2 string function

Hi, I am using SSRS 2008 R2 and trying to replicate a substring tsql function in SSRS using MID but I am not able to make it work properly.

I have my string as 1238 - Johnson's Holding, 463 - Ione Solutions, 37 - Trinity Educational Institute.

I would like to return 1238, 463, 37. How would I write my expression?

Thanks in advance.........