use strict;
use warnings;
my $string = "aabbaaaabbaaabbbbabaabbbaaaa";
my @a;
my $position = 0;
while ( $position < length $string ) {
	my $sstr = substr($string,$position);
    if ( $sstr =~ /(aa)/ ) {
        push @a, $1;
        $position+=$-[0]+1;
    } else {
        $position++;
    }
}
print join("-", @a), "\n";