diff --git a/2024/d4.py b/2024/d4.py
new file mode 100644
index 0000000..98975bb
--- /dev/null
+++ b/2024/d4.py
@@ -0,0 +1,44 @@
+from lib import get_data
+from lib import Grid2D
+
+data = get_data(__file__)
+g = Grid2D(data)
+
+DIRS = {
+    "N": (-1, 0),
+    "E": (0, 1),
+    "S": (1, 0),
+    "W": (0, -1),
+    "NE": (-1, 1),
+    "SE": (1, 1),
+    "SW": (1, -1),
+    "NW": (-1, -1),
+}
+
+t1, t2 = 0, 0
+for row in range(g.n_rows):
+    for col in range(g.n_cols):
+        for d in DIRS.values():
+            coords = [(row + d[0] * i, col + d[1] * i) for i in range(len("XMAS"))]
+            for (r, c), z in zip(coords, "XMAS"):
+                if not (0 <= r < g.n_rows and 0 <= c < g.n_cols and g[(r, c)] == z):
+                    break
+            else:
+                t1 += 1
+
+        coords = [
+            (row - 1, col - 1),
+            (row - 1, col + 1),
+            (row, col),
+            (row + 1, col - 1),
+            (row + 1, col + 1),
+        ]
+        for s in ["MMASS", "MSAMS", "SSAMM", "SMASM"]:
+            for (r, c), z in zip(coords, s):
+                if not (0 <= r < g.n_rows and 0 <= c < g.n_cols and g[(r, c)] == z):
+                    break
+            else:
+                t2 += 1
+
+print(t1)
+print(t2)
diff --git a/README.md b/README.md
index 05a881c..3348db0 100644
--- a/README.md
+++ b/README.md
@@ -294,5 +294,5 @@ and focus. Of course, learning more algorithms and techniques helps.
 - Day 1: `00:01:30   124      0   00:02:49   141      0`
 - Day 2: `00:05:34   686      0   00:08:21   531      0`
 - Day 3: `00:01:48   165      0   00:02:40    56     45`
-- Day 4:
-
+- Day 4: `00:07:47  1101      0   00:24:07  2410      0`
+- Day 5: