#!/usr/bin/perl                                                                                                   
use strict;
use warnings;
use XML::Twig;

my $file = shift;

my $twig = XML::Twig->new( twig_handlers => { inventor => \&inventor } );

$twig->parsefile($file);

sub inventor {
    my ( $twig, $inventor ) = @_;
    if ( $inventor->first_child('number')->text eq "1" ) {
        print $inventor->first_child('country')->text . qq(\n)
          . $inventor->first_child('city')->text . qq(\n)
          . $inventor->first_child('upper-name')->text . qq(\n)
          . $inventor->first_child('name')->text . qq(\n);
    }
}

__END__