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

my $str = do {local $/; <DATA>};
$str =~ s/\s+//g;
my $len = length $str;

while (--$len > 780) {
    printf "%3d : %s\n", $_, substr( $str, $_, $len )
        for 1 .. ( length( $str ) - $len );
}