How to get bar numbers very close to the staff?

[Marc Mouries]

I'd like to get bar numbers very close to the staff to avoid confusing 
them with fingering.
Through Google i could find how to change the position UP or DOWN but i 
could not find how to reduce the space between the bar number and the staff.

Here is the snippet for testing i created.
% test bar number close to the staff to avoid confusion with fingering
\version "2.13.40"

melody = \relative c' { c1-1 c1_1 c'1-1 c'1-1 }

\score {
   \new Staff {
     % Layout Settings
     \override Score.BarNumber #'break-visibility = #all-visible
     \override Score.BarNumber #'font-size = #-4
     \override Score.BarNumber #'direction = #DOWN
     % Melody
      \melody
    }
}

--Marc

test bar number close to staff.ly
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test bar number close to staff.pdf
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