$ perl -we 'for (qw"14/3 03-14") { m"^(?:(?<m>\d\d)-(?<d>\d\d)|(?<d>\d{1,2})/(?<m>\d{1,2}))$" or die; print "$_ => month=$+{m}, day=$+{d}.\n"; }'
14/3 => month=3, day=14.
03-14 => month=03, day=14.