#!/usr/bin/env perl use warnings; use strict; my %holidays; my %common; while () { chomp; next if /^\s*$/ || /^\#/; my $aref = [split /,/, $_]; push @{$holidays{$aref->[2]}}, $aref->[5]; ++$common{$aref->[5]}; } my $countries = keys %holidays; for my $country (keys %holidays) { @{$holidays{$country}} = grep {$common{$_} != $countries} @{$holidays{$country}}; }