diff --git a/days/input/day10_input b/days/input/day10_input
new file mode 100644
index 0000000..3eb93ec
--- /dev/null
+++ b/days/input/day10_input
@@ -0,0 +1,36 @@
+#.....#...#.........###.#........#..
+....#......###..#.#.###....#......##
+......#..###.......#.#.#.#..#.......
+......#......#.#....#.##....##.#.#.#
+...###.#.#.......#..#...............
+....##...#..#....##....#...#.#......
+..##...#.###.....##....#.#..##.##...
+..##....#.#......#.#...#.#...#.#....
+.#.##..##......##..#...#.....##...##
+.......##.....#.....##..#..#..#.....
+..#..#...#......#..##...#.#...#...##
+......##.##.#.#.###....#.#..#......#
+#..#.#...#.....#...#...####.#..#...#
+...##...##.#..#.....####.#....##....
+.#....###.#...#....#..#......#......
+.##.#.#...#....##......#.....##...##
+.....#....###...#.....#....#........
+...#...#....##..#.#......#.#.#......
+.#..###............#.#..#...####.##.
+.#.###..#.....#......#..###....##..#
+#......#.#.#.#.#.#...#.#.#....##....
+.#.....#.....#...##.#......#.#...#..
+...##..###.........##.........#.....
+..#.#..#.#...#.....#.....#...###.#..
+.#..........#.......#....#..........
+...##..#..#...#..#...#......####....
+.#..#...##.##..##..###......#.......
+.##.....#.......#..#...#..#.......#.
+#.#.#..#..##..#..............#....##
+..#....##......##.....#...#...##....
+.##..##..#.#..#.................####
+##.......#..#.#..##..#...#..........
+#..##...#.##.#.#.........#..#..#....
+.....#...#...#.#......#....#........
+....#......###.#..#......##.....#..#
+#..#...##.........#.....##.....#....
\ No newline at end of file
diff --git a/days/test_day10.py b/days/test_day10.py
new file mode 100644
index 0000000..2cfc16b
--- /dev/null
+++ b/days/test_day10.py
@@ -0,0 +1,25 @@
+from math import atan2
+import os
+from typing import Tuple
+
+
+inputfile = os.path.join(os.path.dirname(__file__), "input/day10_input")
+
+
+def calc_arc(origin: Tuple[int, int], target: Tuple[int, int]) -> float:
+    return atan2(target[0] - origin[0], target[1] - origin[1])
+
+
+def test_day10a():
+    with open(inputfile) as fp:
+        lines = [x.rstrip() for x in fp.readlines()]
+    asts = [(x, y)
+            for x, line in enumerate(lines)
+            for y, m in enumerate(line)
+            if m == '#']
+
+    max = 0
+    for my in asts:
+        angles = {calc_arc(my, target) for target in asts}
+        max = len(angles) if len(angles) > max else max
+    assert max == 303