print for map{
     ## remove them once sorted
     unpack 'x[nn]A*', $_
 } sort map {
     ## prefix year & month in binary form
     my( $alpha, $num ) = m[^(\S+?)\s*(\d+)$];
     $num += 2000 if $num <= 49;
     $num += 1900 if $num <= 99;
     pack 'nnA*', $num, $months{ $alpha }, $_;
 } <DATA>;