diff --git a/deps.edn b/deps.edn
index aa775c4..a57e713 100644
--- a/deps.edn
+++ b/deps.edn
@@ -1,3 +1,4 @@
 {:paths ["src" "cookies"]
  :deps {org.clojure/clojure {:mvn/version "1.12.0"}
-        clj-http/clj-http {:mvn/version "3.13.0"}}}
+        clj-http/clj-http {:mvn/version "3.13.0"}
+        org.clojure/math.combinatorics {:mvn/version "0.3.0"}}}
diff --git a/src/day10.clj b/src/day10.clj
new file mode 100644
index 0000000..655cc45
--- /dev/null
+++ b/src/day10.clj
@@ -0,0 +1 @@
+(ns day10)
diff --git a/src/day8.clj b/src/day8.clj
new file mode 100644
index 0000000..d39c628
--- /dev/null
+++ b/src/day8.clj
@@ -0,0 +1,66 @@
+(ns day8
+  (:require [mapped-area]
+            [helpers :refer [get-input]]
+            [clojure.math.combinatorics :refer [combinations]]))
+
+(def test-city
+"............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............")
+
+(def test-city2
+"..........
+..........
+..........
+....a.....
+........a.
+.....a....
+..........
+..........
+..........
+..........")
+
+(def input
+  (->
+   test-city
+   ;;(get-input 8)
+   mapped-area/read-mapped-area))
+
+(defn antinodes [a [[x1 y1] [x2 y2]]]
+  (let [xd (abs (- x1 x2))
+        yd (abs (- y1 y2))
+        a1 [(+ (max x1 x2) xd)
+            (+ (max y1 y2) yd)]
+        a2 [(- (min x1 x2) xd)
+            (- (min y1 y2) yd)]]
+    (filter (partial mapped-area/mapped? a) [a1 a2])))
+
+(defn antennas [a]
+  (reduce
+   (fn [m [coord value]]
+     (if (= value \.)
+       m
+       (update m value #(conj % coord))))
+   {}
+   (mapped-area/mapped-area-indexed-seq a)))
+
+(defn antenna-pairs [a]
+  (mapcat (fn [[_ a]] (combinations a 2)) (antennas a)))
+
+(defn find-antinodes [m]
+  (let [a (mapped-area/read-mapped-area m)]
+    (->> (antenna-pairs a)
+         (mapcat #(antinodes a (vec %))))))
+
+(def r (find-antinodes test-city2))
+(println r)
+(println (set r))
diff --git a/src/mapped_area.clj b/src/mapped_area.clj
index 2efeb19..49bb087 100644
--- a/src/mapped_area.clj
+++ b/src/mapped_area.clj
@@ -71,3 +71,8 @@ ijkl")
 (test #'h)
 (test #'w)
 (test #'mapped?)
+
+(defn mapped-area-indexed-seq [a]
+  (for [x (range (w a))
+        y (range (h a))]
+    (vector [x y] (get-in a [x y]))))