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    my @a= qw( a b c   e  h j   l m n p       );
    my @b= qw(   b c d e f  j k l m     r s t );
    my @diff= easy( \@a, \@b );

  #         @a      @b        @a       @b
  # same?  range   range    values   values
  (   0,   0=>0,   0=>-1,  #    a  !
...
      1,   6=>7,   7=> 8,  #  l m  =  l m
      0,   8=>9,   9=>11,  #  n p  !  r s t
  );

    my @a= qw( a b c   e  h j   l m n p       );
    my @b= qw(   b c d e f  j k l m     r s t );
    my $diff= easy( \@a, \@b );
...
            print "<b>$b</b>"   if  "" ne $b;
        }
    }

    $_ .= $/   for  @a, @b;
    my $diff= easy( \@a, \@b );
    while(  @$diff  ) {
...
            }
        }
    }

-a
 b
 c
...
+r
+s
+t

    my $diff= easy( \@a, \@b );
    while(  @$diff  ) {
        my( $same, $aMin, $aMax, $bMin, $bMax )=
...
            print "> $_";
        }
    }

1,1d0
< a
3a3,3
...
> r
> s
> t

sub easy
{
    my $a= shift;      # array ref
...
    splice @diff, 0, 5   if  $diff[2] < 0  &&  $diff[4] < 0;
    return wantarray ? @diff : \@diff;
}