my @months = qw( January February March April May June July August September October November December );

f(3); # Apr
f(0); # Jan
f(11); # Dec

sub f {
    my $i = shift;  
    print join(',',  @months[$i-2, $i-1, $i]), "\n";
}

##</code><code>##

February,March,April
November,December,January
October,November,December