#!/usr/bin/perl -w

use strict;

my $string = shift || 'AAABCDAAADCBAAABBDAAA';
my @between = split /AAA/, $string, -1;
pop @between;
shift @between;

for (my $i = 0; $i<@between; $i++) {
    for (my $j = $i; $j<@between; $j++) {
        print join "AAA", "", @between[ $i .. $j ], "\n"
    };
};