#!/usr/bin/perl
use strict;
use warnings;
my %hash;
my @pairs = qw(1 canada 1 us 2 england 3 france 3 russia);
while ( @pairs ) {
    my $key = shift @pairs;
    my $val = shift @pairs;
    push @{ $hash{$key} } , $val;
}
for ( sort keys %hash ) {
    print "$_ # ", join ', ' , @{ $hash{$_} };
    print "\n";
}
__END__
1 # canada, us
2 # england
3 # france, russia