Off topic:Getting Error message "Use of uninitialized value $lines[0] in substitution" in Perl

Question

[hemant.nitjsr]

Try to do manipulation in each file in incremental order. Below is my code n it's giving an error message.

Use of uninitialized value $lines[0] in substitution (s///) at ./Replace.pl line 26.
Use of uninitialized value $lines[1] in substitution (s///) at ./Replace.pl line 27.

As I'm new in Perl World kindly help.

#!/usr/bin/perl -w

use strict;
use warnings;
use 5.010;
use autodie;

use Time::Piece;
use Time::Seconds qw/ ONE_MINUTE /;

use constant DATE_FORMAT => '%Y%m%d%H%M%S';

my $n;

my $directory="/home/tt/Doc/Auto";
opendir(DIR, $directory) or die "couldn't open $directory: $!\n";
my @files = readdir DIR;

foreach (@files) {

  open my $in_fh, '<', $_;
  my @lines = <$in_fh>;
  close $in_fh;

  ++$n;
  $lines[0] =~ s/4947000219\K(4947000219+)/$1+$n/e;
  $lines[1] =~ s{:20140924105028\K(\d+)}{
    my $tp = Time::Piece->strptime($1, DATE_FORMAT);
    ($tp + ONE_MINUTE * 2 * $n)->strftime(DATE_FORMAT);
  }e;

  my $backup = "$_.backup";
  unlink $backup if -f $backup;
  rename $_, $backup;

  open my $out_fh, '>', $_;
  print $out_fh @lines;
  close $out_fh;
}
closedir DIR;