diff --git a/13.hs b/13.hs
new file mode 100644
index 0000000..1044061
--- /dev/null
+++ b/13.hs
@@ -0,0 +1,29 @@
+import Data.List.Split (splitOn)
+import Data.List (findIndex)
+
+type Delay = Int
+type Firewall = (Int, Int)
+(%) = mod
+
+parseLine :: String -> Firewall
+parseLine str =
+    let depth : range : _ = splitOn ": " str
+    in  (read depth, read range)
+
+caught :: Delay -> Firewall -> Bool
+caught delay (depth, range) =
+    (depth + delay) % (2 * (range - 1)) == 0
+
+severity :: [Firewall] -> Int
+severity firewalls =
+    sum . map (\firewall -> uncurry (*) firewall * fromEnum (caught 0 firewall)) $ firewalls
+
+anyCaught :: [Firewall] -> Delay -> Bool
+anyCaught firewalls delay =
+    or  . map (caught delay) $ firewalls
+
+main :: IO ()
+main = do
+    firewalls <- fmap (map parseLine . lines) $ readFile "13.txt"
+    print $ severity firewalls
+    print $ findIndex not $ map (anyCaught firewalls) [0..]
\ No newline at end of file
diff --git a/13.txt b/13.txt
new file mode 100644
index 0000000..4926844
--- /dev/null
+++ b/13.txt
@@ -0,0 +1,43 @@
+0: 4
+1: 2
+2: 3
+4: 5
+6: 8
+8: 6
+10: 4
+12: 6
+14: 6
+16: 8
+18: 8
+20: 6
+22: 8
+24: 8
+26: 8
+28: 12
+30: 12
+32: 9
+34: 14
+36: 12
+38: 12
+40: 12
+42: 12
+44: 10
+46: 12
+48: 12
+50: 10
+52: 14
+56: 12
+58: 14
+62: 14
+64: 14
+66: 12
+68: 14
+70: 14
+72: 17
+74: 14
+76: 14
+80: 20
+82: 14
+90: 24
+92: 14
+98: 14
\ No newline at end of file