my @files= <*>;
@files= do {
    my @mo= qw(jan feb mar apr may jun
        jul aug sep oct nov dec);
    my %mo; @mo{@mo}= 0..$#mo;
    grep {
        s/^[^-]*-//
    } sort grep {
        # Replace "JAN1" with "a01-JAN1":
        s/^(...)(\d\d?)/sprintf
            "%s%02d-%s",$mo{lc$1},$2,$1.$2/e
            or  $_= "?-$_";
        1;
    } @files;
};