Using the date field below, I would like to create a new field that subtracts today (current month/year) from this field's format below. There are some fields that do not have a date value ('-' or blank) - in those cases output a '-'.

Current Formula:

=1*DATEDIF(DATE(LEFT(A2,4),MID(A2,6,2),1),TODAY(),"m")

Current Formula is working, but outputs #VALUE instead of '-' when there is no value. How would I go about updating/fixing that?

Column A: Column B(Expected Value):

2019-03 04

2019-07 00

2019-06 01

2019-05 02

2019-04 03

- -

Question 2:

Using the date field below, how would I count the number of days between today and the date below? This field will have some fields with a blank value and some dates in Column C could be in the past. If dates are in the past or are missing so that the calculation is not logical, output a '-'.

Column C Column D (Expected Value):

07/22/2019 2

07/01/2019 -

07/20/2019 0

07/19/2019 -