diff --git a/02b.lisp b/02b.lisp
new file mode 100644
index 0000000..c0d09ab
--- /dev/null
+++ b/02b.lisp
@@ -0,0 +1,48 @@
+(require :uiop)
+(load (sb-ext:posix-getenv "ASDF"))
+(asdf:load-system 'str)
+
+(defun get-range (range)
+  (let ((range (str:split "-" range)))
+    (loop for i from (parse-integer (car range)) to (parse-integer (car (cdr range))) collect i)))
+(get-range "11-22")
+
+(defun get-ranges (instr)
+  (loop for range in
+        (str:split "," (string-trim '(#\Newline) instr))
+        collect
+        (get-range range)))
+(get-ranges "1-3,4-5")
+
+(defun match-sequence (seq-len seq remaining)
+  (setq rem-len (length remaining))
+  (cond
+    ((not (integerp (/ rem-len seq-len))) nil)
+    ((string= seq remaining) t)
+    ((not (string= seq (subseq remaining 0 seq-len))) nil)
+    (t (match-sequence seq-len seq (subseq remaining seq-len)))))
+(match-sequence 2 "12" "2212")
+(match-sequence 2 "12" "121")
+(match-sequence 2 "12" "1212")
+(match-sequence 2 "12" "12")
+
+(defun validate-product-id (product-id)
+  (setq product-id (format nil "~A" product-id))
+  (not
+    (loop for seq-len from 1 to (floor (/ (length product-id) 2))
+      when (match-sequence seq-len (subseq product-id 0 seq-len) (subseq product-id seq-len))
+      do (+ 1 2); not sure how to remove this?
+      and return t)))
+(validate-product-id 1212)
+(validate-product-id 121212)
+(validate-product-id 123)
+(validate-product-id 1234)
+
+(defun sum-all-invalid-ids (text)
+  (reduce #'+
+    (remove-if #'validate-product-id
+      (reduce #'append
+        (get-ranges text)))))
+
+(sum-all-invalid-ids (uiop:read-file-string "02example.txt"))
+(sum-all-invalid-ids (uiop:read-file-string "02data.txt"))