Calculated field - need help

Hi every one.
I have a calculated field like this:

CASE
WHEN (julianday(end) - julianday(begin)) = 0 THEN '1'
ELSE (julianday(end) - julianday(begin))
END

In tablegrid it shows like this

           begin                       end           calc_field
1.  08.10.2016               08.10.16            1
2.  05.10.2016               08.10.16          3.0

In the given example the first one is norm, but the second one must be 3, as you see it is 3.0. Help me to make it just 3.