part2

09/2.pl

@@ -0,0 +1,24 @@
+use 5.20.0;
+
+my $stream = <>;
+chomp $stream;
+
+my $garbage;
+$stream = clean_stream($stream);
+
+say $garbage;
+
+use experimental qw/signatures /;
+
+sub clean_stream($s) {
+
+    return $s unless $s =~ s/^(.*?)<//;
+
+    while( $s =~ s/^(.*?)(!.|>)// ) {
+        warn $1;
+        $garbage += length $1;
+        last if $2 eq '>';
+    }
+
+    clean_stream($s);
+}

09/test

@@ -0,0 +1 @@
+{{<!!>},{<!!>},{<!!>},{<!!>}}