#!/usr/bin/perl -slw

use strict;
use warnings 'all';
use POSIX 'ceil';

our $N //= 3;
our $M //= 1e6;

my $each = ceil($M / $N);
my $last = 0;
my @ranges = ( );

for( 1..$N )
{
  last unless $last <= $M;
  my $part = [ $last => $_ == $N ? $M : $last + ( $_ == $N ? $each : $each - 1 ) ];
  $part->[1] = $M if $_ == $N;
  $last += $each;
  push @ranges, $part;
}# end for()

printf "%2d : from %7d to %7d (%7d)\n",
    $_, @{ $ranges[ $_ ] },
    $ranges[ $_ ][ 1 ] - $ranges[ $_ ][ 0 ] + 1
    for 0 .. $#ranges;