use strict;
use warnings;

my $office = shift or die "Usage: $0 office\n";

my %h;

my $infile = "employees.txt";
open F, "< $infile" or die "read $infile - $!\n";

while (<F>)
{
    chomp;
    my( $name, $email, $offices ) = split /\t/;
    $offices or next;
    $h{$_}{$name} = $email
        for split /,\s*/, $offices;
}

close F;

print "$_\t$h{$office}{$_}\n"
    for sort keys %{ $h{$office} };
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