use strict ;
use warnings ;

my @directories = qw( /files1 /files2) ;

my $min_size = 1024 ; 
my $max_size = 1048576 ; #1MB

my @small_files ;
my @big_files ;
for my $dir (@directories) {
  for my $file (read_dir( $dir, prefix => 1 )) {
    next if (! -f $file || -s $file < $min_size) ;

    if (-s $file <= $max_size} {
      push(@small_files, $file) 
    }
    else {
      push(@big_files,   $file) ;
    }
  } 
}