formula for a field in the Crystal report 2014

Hi experts,

I am using CR 2014.

Am trying to create a formula in the Cyrstal report for a field as below.

nnm1.SeriesName = "CHN-16"

now, i want the formula to separate the nnm1.seriesname as above by "-".

for example : i want only CHN instead of CHN-16

Thanks in advance,

REgards,

Dwaraka