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

sub pa { print join(', ', @_), "\n" }

die "usage: $0 <number of items> <number of columns>"
  unless $#ARGV == 1;

my @IN = 1 .. $ARGV[0];
my $COLS = $ARGV[1];
my @OUT = ();

pa @IN;

for my $i (0 .. $COLS-1) {
  for (my $j = $i; $j<=$#IN; $j+=$COLS)   
    { push @OUT, $IN[$j] }
  push @OUT, "{}"                               
}

pa @OUT;