diff --git a/elisp/day-3/solution.el b/elisp/day-3/solution.el
index 826ada1..ac6fca9 100755
--- a/elisp/day-3/solution.el
+++ b/elisp/day-3/solution.el
@@ -33,6 +33,9 @@
       (+ (- char ?A) 26 1)
     (+ (- char ?a) 1)))
 
+(defun solution-3-way-intersection (a b c)
+  (seq-intersection (seq-intersection a b) c))
+
 (defun solution-part-1 (input)
   (let* ((char-lists (seq-map 'string-to-list input))
          (split-into-halves (seq-map (lambda (char-list)
@@ -49,12 +52,29 @@
          (item-priorities (seq-map 'solution-letter-priority common-items)))
     (apply '+ item-priorities)))
 
+(defun solution-part-2 (input)
+  (let* ((char-lists (seq-map 'string-to-list input))
+         (groups (seq-split char-lists 3))
+         (common-items (seq-map (lambda (group)
+                                  (car (seq-intersection (seq-intersection (car group)
+                                                                           (cadr group))
+                                                         (caddr group))))
+                                groups))
+         (item-priorites (seq-map 'solution-letter-priority common-items)))
+    (apply '+ item-priorites)))
+
 (ert-deftest solution-part-1-example ()
   (should (equal (solution-part-1 (aoc-read-file-lines solution-example-input)) 157)))
 
 (ert-deftest solution-part-1 ()
   (should (equal (solution-part-1 (aoc-read-file-lines solution-input)) 7878)))
 
+(ert-deftest solution-part-2-example ()
+  (should (equal (solution-part-2 (aoc-read-file-lines solution-example-input)) 70)))
+
+(ert-deftest solution-part-2 ()
+  (should (equal (solution-part-2 (aoc-read-file-lines solution-input)) 2760)))
+
 (when noninteractive
   (ert-run-tests-batch))