c:\@Work\Perl\monks>perl -wMstrict -le
"my %months_name = qw(
    1 January     2 February  3 March      4 April
    5 May         6 June      7 July       8 August
    9 September  10 October  11 November  12 December
    );
 ;;
 my @months = map $months_name{$_}, sort { $a <=> $b } keys %months_na
+me;
 ;;
 for my $n (1 .. 12) {
   my @prev_3 = map $n-1+$_, -3 .. -1;
   @prev_3 = @months[ @prev_3 ];
   print qq{(@prev_3) before $months_name{$n} (month $n)};
   }
"
(October November December) before January (month 1)
(November December January) before February (month 2)
(December January February) before March (month 3)
(January February March) before April (month 4)
(February March April) before May (month 5)
(March April May) before June (month 6)
(April May June) before July (month 7)
(May June July) before August (month 8)
(June July August) before September (month 9)
(July August September) before October (month 10)
(August September October) before November (month 11)
(September October November) before December (month 12)
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