#! /usr/bin/env perl
use v6;
use fatal; # or is this default?
die "usage: $*PROGRAM_NAME <dir>" unless @*ARGS == 1;

chdir @*ARGS[0];
my @files = grep { $_ ne '.'&'..' } readdir '.';
loop (my $i = 0; @files; $i++) {
  mkdir $i;
  rename $_, "$i/$_ for splice @files, 0, 1000;
}