use strict;
use warnings;
use Data::Dump qw/pp/;

my %count;

for my $c0 (0..9){
   for my $c1 (0..9){
      for my $c2 (0..9){
         for my $c3 (0..9) {
            my @c = sort {$a <=>$b} ($c0,$c1,$c2,$c3);
            #print "@c\t:\t";
            my @allowed;
            for my $i (1..3) {
               if ( $c[$i] != $c[$i-1]    &&   $c[$i] != $c[$i-1]+1 ) {
                  push @allowed, $c[$i] 
               }
            }
            #print "@allowed\n";
            $count{join "",@allowed}++
         }
      }
   }
}



my @length;
my $average;
for my $k (keys %count){
   my $len = length $k;
   $length[$len]++;
   $average+= $len* $count{$k}/10000;
}

warn '@length: ', pp \@length;
warn 'average #characters: group/line',pp [$average,$average*9];


my  $combies =0;
$combies+= $length[$_] for 0..3;
#$combies=93;

warn "# possible combinations: ", $combies;


my $upper_bound= log($combies)/log(2)*9;
warn 'Upper bound bits, bytes', pp [$upper_bound, $upper_bound/8];

#warn "ranking", pp [ sort {$b <=>$a} values %count ];

warn 'probabilities: ',pp \%count;