#!/usr/bin/perl

use strict;

my ($key,$name,%countries);
open (my $fh1,"<","files/country_listv1.txt") or die $!;
while(<$fh1>){
  if (!exists $countries{$_}){
    $countries{$_} = '1';
  }
}
open (my $fh2,">","files/country_listv2.txt") or die $!;
foreach $key (sort keys %countries){
    print $fh2 $key;
  
} 
close($fh1,$fh2);