$ perl test.pl
Use of uninitialized value $file in scalar chomp at test.pl line 10.

##</code><code>##

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

my $path2file = 'Q.txt';

open my $fh, '<', $path2file;
chomp(my @column = <$fh>);
close $fh;

my $number=0;
while($number <= $#column) { #go through the array from 0 to the last element
    my $j;
    my $count=0;
    foreach ($j=$number; $j < $#column; $j++) { #select the numbers from the beginning of the line in the current and next element
	my $d=($column[$j]=~/(\d+)/)[0] - ($column[$j+1]=~/(\d+)/)[0]; #difference
	last if abs($d)!= 1; #if differ more than 1 - leave
	$count+=$d; #accumulate the difference
    }
    if(abs($count)>=7) {
	chomp($column[$_]);
	$column[$_]=$column[$_]. "\tIN\n" for $number..$j; #IN if >8
	$number=$j+1;
    }
    if (abs($count)<8) {
	chomp($column[$number]);
	$column[$number] = $column[$number]."\tOUT\n"; #OUT if < 8
	$number++;
    }
}
print for @column;

__END__

$ perl test.pl
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
Use of uninitialized value in subtraction (-) at test.pl line 16.
5	Q	CAA	OUT
	OUT
16	Q	CAG	OUT
	OUT
21	Q	CAA	OUT
	OUT
74	Q	CAA	OUT
	OUT
80	Q	CAG	OUT
	OUT
82	Q	CAG	OUT
	OUT
84	Q	CAG	OUT
	OUT
85	Q	CAG	OUT
	OUT
89	Q	CAG	OUT
	OUT
90	Q	CAG	OUT
	OUT
91	Q	CAG	OUT
	OUT
92	Q	CAG	OUT
	OUT
93	Q	CAA	OUT
	OUT
94	Q	CAG	OUT
	OUT
95	Q	CAG	OUT
	OUT
96	Q	CAG	OUT
	OUT
98	Q	CAG	OUT
	OUT
99	Q	CAG	OUT
	OUT
100	Q	CAG	OUT