diff --git a/2018/02-test.txt b/2018/02-test.txt
new file mode 100644
index 0000000..46a5a08
--- /dev/null
+++ b/2018/02-test.txt
@@ -0,0 +1,7 @@
+abcde
+fghij
+klmno
+pqrst
+fguij
+axcye
+wvxyz
\ No newline at end of file
diff --git a/2018/02.rkt b/2018/02.rkt
new file mode 100644
index 0000000..1c224be
--- /dev/null
+++ b/2018/02.rkt
@@ -0,0 +1,37 @@
+#lang debug br
+
+(define fp (open-input-file "02.txt"))
+
+(define ids
+  (map string-trim (port->lines fp)))
+
+(define ((cluster len) chars)
+  (for/or ([group (in-list (group-by values chars char=?))])
+    (= len (length group))))
+
+(define (★)
+  (define charss (map string->list ids))
+  (define twos (length (filter (cluster 2) charss)))
+  (define threes (length (filter (cluster 3) charss)))
+  (* twos threes))
+
+(define (differ-by-one? id id2)
+  (= (length (common-chars id id2)) (sub1 (string-length id))))
+
+(define (common-chars id id2)
+  (for/list ([c (in-string id)]
+             [c2 (in-string id2)]
+             #:when (char=? c c2))
+    c))
+
+(define (★★)
+  (list->string
+   (for*/first ([id (in-list ids)]
+                [id2 (in-list (cdr ids))]
+                #:when (differ-by-one? id id2))
+     (common-chars id id2))))
+
+(module+ main
+  (require rackunit)
+  (check-equal? (time (★)) 6696)
+  (check-equal? (time (★★)) "bvnfawcnyoeyudzrpgslimtkj"))
\ No newline at end of file
diff --git a/2018/02.txt b/2018/02.txt
new file mode 100644
index 0000000..420afc0
--- /dev/null
+++ b/2018/02.txt
@@ -0,0 +1,250 @@
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\ No newline at end of file
diff --git a/2018/stub.rkt b/2018/stub.rkt
new file mode 100644
index 0000000..b5723bf
--- /dev/null
+++ b/2018/stub.rkt
@@ -0,0 +1,12 @@
+#lang debug br
+
+#;(define (★)
+  )
+
+#;(define (★★)
+  )
+
+#;(module+ main
+  (require rackunit)
+  (check-equal? (time (★)) 454)
+  (check-equal? (time (★★)) 566))
\ No newline at end of file