I'm pretty new and I'm playing with the flows. 
I have a subject of the case (generated via mail to the case) that is like this
NRT_N_22F26234-55_pier_T_delivery
It might be also 
N_22F26234-55_pier_T_delivery
or
22F26234-55_pier_T_rejected
I would like to extract
22F26234-55

my idea is to use regex expression ([0-9]+F[0-9]+-[0-9]+) to identify the position of the regex string... is it possible???

grazie