open(FILE, '/location/data/p4.txt') or die "Cant't open file: $!\n";

##</code><code>##

    use strict;
    use warnings;
    use autodie qw( open close );

    # ...

    my $file = shift; # The input file name is a command-line argument

    open my $fh, '<:encoding(ASCII)', $file; # Or whatever the correct character encoding is

    # ...

    close $fh;

##</code><code>##

    my %myhash = ();
    my @data = ();

    chomp(@data = <FILE>);
    foreach (@data)    {
        %myhash = (@data => $k++);
    }

##</code><code>##

    my %total_values_by;

    while (my $value = <$fh>) {
        chomp $value;
        $total_values_by{$value}++;
    }