#!/usr/bin/perl
#
use strict;
use warnings;

my $intervalStr = q{1..25};

my @subIntervalStrs = qw{
   3..12
   7..14
   11..19
   12..17
   };

my ( $begin, $end ) = split m{\.\.}, $intervalStr;
my @subIntervals =
   sort { $a->{ min } <=> $b->{ min } }
   map
   {
       my ( $min, $max ) = split m{\.\.}, $_;
       { min => $min, max => $max };
   }
   @subIntervalStrs;

for my $value ( $begin .. $end )
{
    my $count = 0;

    shift @subIntervals while
       @subIntervals
       and
       $value > $subIntervals[ 0 ]->{ max };

    for my $subInterval ( @subIntervals )
    {
        if ( $value < $subInterval->{ min } )
        {
            last;
        }
        elsif ( $value > $subInterval->{ max } )
        {
            next;
        }
        else
        {
            $count ++;
        }
    }

    printf qq{%4d => %d\n}, $value, $count;
}

##</code><code>##

   1 => 0
   2 => 0
   3 => 1
   4 => 1
   5 => 1
   6 => 1
   7 => 2
   8 => 2
   9 => 2
  10 => 2
  11 => 3
  12 => 4
  13 => 3
  14 => 3
  15 => 2
  16 => 2
  17 => 2
  18 => 1
  19 => 1
  20 => 0
  21 => 0
  22 => 0
  23 => 0
  24 => 0
  25 => 0