use warnings;
use strict;

my $filename = '/tmp/input.txt';
open my $fh, '<:encoding(UTF-8)', $filename or die "$filename: $!";
my %seen;
while (<$fh>) {
	chomp;
	my @fields = split /,/;
	$seen{$fields[1]}++
}
close $fh;
my @data = sort keys %seen;
print $_,"\n" for @data;