use strict ;
use warnings ;
##updated according to suggestions
my $string="atccatccctttaat" ;
my $left_out=2 ;
my $template = "x$left_out" ;
$template .= "a3" x ((length($string)-$left_out)/3) ;
my @array=unpack($template, $string) ;
local $"="\n" ;
print "@array" ;