#!/usr/bin/perl
use strict;
use warnings;

my %COLORS = (
  red => undef,
  green => undef,
  blue => undef,
);

sub change{
  my($R,$G,$B) = @_;
  $COLORS{red} = $R;
  $COLORS{green} = $G;
  $COLORS{blue} = $B;
}

change(11);

print $COLORS{red};