diff --git a/Cargo.lock b/Cargo.lock
index 07cc225..76f3d59 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "arrays"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2dbdbb2877d26e0647c6b8125802b2ecf2dc2a28d864dde41e6f9b9a54da08fe"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -104,6 +110,9 @@ version = "0.1.0"
 [[package]]
 name = "day06"
 version = "0.1.0"
+dependencies = [
+ "itermore",
+]
 
 [[package]]
 name = "day07"
@@ -246,6 +255,35 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "iterchunks"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ceb61464343bc874be283540bf6bb148d6e5b61023bc5acbb9f969b56c806780"
+dependencies = [
+ "arrays",
+]
+
+[[package]]
+name = "itermore"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0331e230609e456fccf9d3b3d4f273a1b3f6b601ed37e943dc197fe5d24bb4da"
+dependencies = [
+ "arrays",
+ "iterchunks",
+ "iterwindows",
+]
+
+[[package]]
+name = "iterwindows"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3cbf3a88c019a9667dbea976f47cf797ffc8d765c53d893e60f27576be6333b0"
+dependencies = [
+ "arrays",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.4.0"
diff --git a/day06/Cargo.toml b/day06/Cargo.toml
index dcc1747..377f632 100644
--- a/day06/Cargo.toml
+++ b/day06/Cargo.toml
@@ -8,3 +8,4 @@ build = true
 app = true
 
 [dependencies]
+itermore = "0.5.0"
diff --git a/day06/input b/day06/input
new file mode 100644
index 0000000..68bd997
--- /dev/null
+++ b/day06/input
@@ -0,0 +1 @@
+pjbjvjtjljplppjssvtvwtwptptztltbtrrjgrjrzrqrjrbrhbrhrlllbpbdbbzqqgsqshqssjjbsjbsbmbhhmchhrqrcqqbwbqwwqrrznnsbswwwdjwdwmmsvszzlbbgddbgdgfgttzjzrjzrjzzvrvqqgpqggtbgtgvvrhvhtvtjjbpjjfjhjbhbddbjjjmzmtmgmpgmmmljlnljjmpmbpmbmrrlhhlppdgdfgfbbqlbbtffjjgvvnpvpbpttqmmnhhgfgrrwhrrbnbznzccmbmvmmzszsvsbvbccsrslsjsbbtdtwtvttvpvzzvbzzwczwcczhzhwhjhjghgppgpgttdwdhwhphnppqmpqqhthcchdhmhnnbcnbcbbggbfblljttwsswspsggpjjzszcscsmcmdmnngzzhrzrbrhbhzbzvzgvgffnlnljlrrhchhsvhssmpmccncdnccgdgbglgtlggnllsvvpfvpfpbffsgglddjrrzzphhptprtppwrwffzllrbrmrpmpdmpdmpplpspcphcphhgmmqnmmvnmmdvmvsmmqjmmlmlbmlbmlltlptphpnncscbscbcggwhhgjgqjqmjmdjmdjdrrvgvvzlldgdnnvttmmpffdjjvvchcwwbhwbwzzlmlccrttcntccpcgccpgcpggdrrbtrthhlrrbqrrpspdsdldbldblbzbpbgggtngtgqqtwwdjjmmcrmcrcvclcddhllpzpdzzmccrtccfvffccfhccpscctbbbzqzvvllgwlgwgvwwjswjswsvvwhhvjvsjvjmmjhjrhrmrvrnrccmnmzzmdzzbtbvbqvvgzgcgvvvvlltvllbfbqqrppwhpwpffzddzdzwdzzrggmhmfhmhbbzjzsjzzhhjdhhdnndsnssnfffbmffwhwrhhmmbnnbrnrbrrtqtztnzzzzblbhbdhbbfmfqfmmsgszzvfzfmfwfnwfwggwngnqnwqnwqwvwqvwvdvrvjjfnjnmnfmmwzzltztjjqnnnmlmzlmmrcmclcqqhrhdhccdfdvfvccvtcvvdmmtmccwjjcbcrrjmrjrdrffgwwvbvlvsspwpsspzsschssmqsqmqmlqmmqgqfqcqjcjtthjttlddfvvwwjvvtpvvfsvffqnffznzqzszgzmmjttwztwzzhqqccqsqmqnmqqjhqhzhwhvhdddsndsdfftvffwlwnnmmdpmmnhhrqrrclcdlcddhcdcppgrprnpnptnpphgpbqfngdgzvgndwcgrwcsfmhzsvddhzbgjmvvdjjzswvgnpmvgdpwsgbgjzjpsrfdzdzjzzrpplbhsmgddqzjbdzdzltqqwqjzqvwfmcdppbdbprrwzhmnrqclzrnmdjnfbwmvdrwtpwvgscrqgpndqnzbjsbljcbthbpgdjdcdwfhpvjnbsfjdlrjldvvmtfdslrhlfwmvclqrljrqmmjgqfwmfgwdjzzptgcthvtgdswsqjrqvnzmtqldjjcqnfhtvbwhjqlvpptfwjrdpcwvzddgcjzvqbhtsnnnjqqmqlbgvqmvjhvvpbzcbdmhgmcjbfcccsvlzjztvjzrrlhtgwccdcgcptqlmdhmdhvqzfntbjqtsmvqgwsltqntgszllntrljfgfsghtbbcqrdgwqphmbqtzmjqccrgvqpqpchzjstdmmtvntwjqsbcqjgnhzlllcfbpgtgrhwwhqqdlgrlsbzbmchvjnsgpdnmqvtgwqjpgflqgfngjfcfwqzmvvgzmmhbgfnbzvzclwclqdcccgbrrzpwdtprgsvhbgsnbntgrvnzhrnzfzdmnlbnrbqvmjbwpgvjlhbcvsrlqmcsnlrvtfdwtvcbmlndgbctsnmtctjszlpddqmzbtphhhfznwbdfsgppmdmczmhmmrzpllfqqbgvlsrscpfgznhdhgrnnnvrchgvzlqbgvcfghjvlvrvpclfcshbmvglcfrjbzrbcjmjjrfgqthwfrqbgtjldmbnfwllspmwrvstvrltvrlvrtjvprgtgzjlrgclvjhqpfcwcdbdtzwdsdfrtsvtvgjmsszdfqlmhqqlzswjfndswlmhcrhglphvpnfjpbmggbwlmzjchpnrllbjpmgmzjjrqpqgsbrszqhdljcpnclvrvbntgtcdcmhtdhgslhpvdjpvrszfrjhsbvcvtfwvvgczprnpbhmnnlmctbtqdjspgvhvnhwvspwgnjvzllwlnjhfjwsslppmjbfbdnthcpzbcmnnbvhctgwgdvhvlrbltmdnlfcsncqgrmjprshdvvtvcccgzhszcjgczhmhtvmccjpchqshhdzjjhbfpzqdjszdhdvlmgctmwcjprwlsqbcqhlcrfdgnqzfdfvqslmqlppbsvbmjmfbrtdmpmtqvwvppcfzddjzhhzlrrnnhbrlhmzlqwftprfvctnfhfhfzrnrvggfqmqwcwszhtbfjncprgwcqbjlvtnrprlwwghswvprjmsbmqvwnnfggprndvshfvvwtrqjpwghgbppftgzhqjslfzhngwfsjnmjzdsjqgpmglwnjlcgmczgvndszrszcpnzqpbzjmgrfsbjlghwrbqsqdhlnhzsvsgbqhbcdffjlgrbdrrjvclzqpftlhdvvcrvlgvlpnjcqdcbdjtlwnldjhhhzrwsqlhlsztwrznfsszptlrhjmqwmnfwjtjwmmmtvwzhpmjgzgsscbddgvvhpcnhvnggzhbzvvjlmdftpbcsvtsttrvgghptmmcdclbdvmnsdntthfbdznbclwccnlzcvdwzrqgddjszvbdqcjppzrtpnrhfcvvwpjqczgqwzzzvzmlnlzqszvtllftthgwgftjzsndpzzcnqpcvmsdvvfrjdsvfclsqqhsjrrctfvdrlhfmhprjggdcmqrrbqtwnrllhhztvjgmzqszbvqfwsgllvhsvfrjffvdscwjzqlzlwdpgthddpgzjfdbdqpsnntwpslvsdpqfnsgcllszcjwvtqhwhpfrlfdgwrfmgfpjmvnstrmtfcvgwlqdfqvntltqtrmjjtwcthvwntqgvncssplnmvlnstlcphvlcmvjnstwldtntchcbmzmlzhgjfbrdlgzvqpgcndmfdnmcnwhmpdnpqstfddddcrpgrpfwfbzjqtnzwwqpzrqpmrjpfznrndfgwhtlvrcrphqfjzjbttwhgnsngqwvnsbvcqtjlmhvmnmnnmjcmlpnpgmrqsbmgljvsfqvrlljqzmzqqbgpvcrwdjmgsglssjswmnvtshhfqjhqmfmvcjwfpwsppgtrqsbhhcdljnjphnjszqpvdplbwzpwmmpwfhmhngtllzqvpmgdctmfqwwqjszssmjhwnrjdtmmvpdnwlqtcbpfcmwtbjmmsmmdpqgzdhsblgjmjbpzgqvqhnggtwmhztbbhlflllgwblncjjsngdgvsfdmsbsvlpnjjzqqbzhsqclmjnnmmwlpvtgwqmcgmrqdwdddlgbvhntbztbjnqhdlggnzwsdtdzprgddhtcttjrcpszgchtfwqjsdlnbntfwqpzpfsqrqjhthmcfszwtwcqwbvfzdnrrpmzjdrhsgmhfbsldvcrjdwvpqpszzlvbptljgvccqsdhhnztjpghbvhfptgplqdvldjzfthpspwvgljwnnndwrqzbrstnqbvrrcghssnrpvtrhmvcmbngwndzfswmgjwnnzqdcjhpthcgvthsnwqzrnzrvdjmctchhsbnrtvctzqfpcjhzmhnfjlqftbjztfbcppgmwvrzzrvlcpnpwwpvtcpdplrcfpgfqjtlfjtphhpcltwqcbqbznbtjrtdrpgtvzmgsclhpptrssqqbctdrftqzmwjmrmjtgmjmsnbnspjvcqpqnmgzgjrmfhghvsfsdqnbdjsbcpczsdswdcvhfzlgpzbtmztcnbpcvjnlcdmmlbtwzsfqtfnlrwjtwmgslcgptgbdsfwdhppvfwbbgdfdqtrbncbznmqtchzsdzlhlhjnnbpdvnnfjrdfbdqmvcb
diff --git a/day06/input.test b/day06/input.test
new file mode 100644
index 0000000..5a2b0a7
--- /dev/null
+++ b/day06/input.test
@@ -0,0 +1 @@
+mjqjpqmgbljsphdztnvjfqwrcgsmlb
\ No newline at end of file
diff --git a/day06/src/bitmask.rs b/day06/src/bitmask.rs
new file mode 100644
index 0000000..5d58db5
--- /dev/null
+++ b/day06/src/bitmask.rs
@@ -0,0 +1,41 @@
+use std::ops::{BitAnd, BitOr};
+
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
+pub struct Bitmask(u64);
+
+impl Bitmask {
+    pub const fn from_alpha(alpha: &u8) -> Self {
+        // 'a' is the LSB, 'Z' is MSB
+        if *alpha <= b'Z' {
+            Self(1 << (alpha - b'A' + 26))
+        } else {
+            Self(1 << (alpha - b'a'))
+        }
+    }
+    /// Get the priority from a rucksack entry
+    pub const fn count_ones(self) -> u32 {
+        self.0.count_ones()
+    }
+}
+
+impl const BitOr for Bitmask {
+    type Output = Self;
+
+    fn bitor(self, rhs: Self) -> Self::Output {
+        Self(self.0 | rhs.0)
+    }
+}
+
+impl const BitAnd for Bitmask {
+    type Output = Self;
+
+    fn bitand(self, rhs: Self) -> Self::Output {
+        Self(self.0 & rhs.0)
+    }
+}
+
+impl std::fmt::Binary for Bitmask {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{:b}", self.0)
+    }
+}
diff --git a/day06/src/main.rs b/day06/src/main.rs
index e7a11a9..f40d7a3 100644
--- a/day06/src/main.rs
+++ b/day06/src/main.rs
@@ -1,3 +1,108 @@
-fn main() {
-    println!("Hello, world!");
+#![feature(array_windows)]
+#![feature(const_trait_impl)]
+#![feature(const_ops)]
+use itermore::{self, IterArrayWindows};
+
+use std::{
+    fs::File,
+    io::{BufRead, BufReader},
+    ops::BitOr,
+};
+
+use bitmask::Bitmask;
+
+mod bitmask;
+
+#[derive(Debug, Default, PartialEq, Eq)]
+enum SolvePuzzle {
+    First,
+    #[default]
+    Second,
+}
+
+fn solve_puzzle<const LEN: usize, B: BufRead>(reader: B) -> usize {
+    reader
+        .bytes()
+        .map(Result::unwrap)
+        .filter(u8::is_ascii_alphabetic)
+        .map(|byte| Bitmask::from_alpha(&byte))
+        .array_windows::<LEN>()
+        .enumerate()
+        .find_map(|(position, window)| {
+            if window
+                .iter()
+                .copied()
+                .reduce(BitOr::bitor)
+                .unwrap_or_default()
+                .count_ones()
+                == LEN as u32
+            {
+                Some(position + LEN)
+            } else {
+                None
+            }
+        })
+        .unwrap_or_default()
+}
+
+fn main() {
+    let mut args = ::std::env::args().skip(1);
+    let file = args.next().unwrap_or_else(|| String::from("./input"));
+    let solve = args
+        .next()
+        .map(|arg| match arg.as_str() {
+            "first" => SolvePuzzle::First,
+            "second" => SolvePuzzle::Second,
+            _ => unreachable!(),
+        })
+        .unwrap_or_default();
+    let file = BufReader::new(File::open(file).expect("Input file not found"));
+    let solution = match solve {
+        SolvePuzzle::First => solve_puzzle::<4, _>(file),
+        SolvePuzzle::Second => solve_puzzle::<14, _>(file),
+    };
+    println!("{}", solution);
+}
+
+#[cfg(test)]
+mod tests {
+    use std::io::Cursor;
+
+    use super::*;
+
+    #[test]
+    fn first_with_example_1() {
+        let reader = Cursor::new(include_str!("../input.test"));
+        assert_eq!(solve_puzzle::<4, _>(reader), 7);
+    }
+
+    #[test]
+    fn second_with_example_1() {
+        let reader = Cursor::new(include_str!("../input.test"));
+        assert_eq!(solve_puzzle::<14, _>(reader), 19);
+    }
+
+    #[test]
+    fn first_with_additional_examples() {
+        let reader = Cursor::new("bvwbjplbgvbhsrlpgdmjqwftvncz");
+        assert_eq!(solve_puzzle::<4, _>(reader), 5);
+        let reader = Cursor::new("nppdvjthqldpwncqszvftbrmjlhg");
+        assert_eq!(solve_puzzle::<4, _>(reader), 6);
+        let reader = Cursor::new("nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg");
+        assert_eq!(solve_puzzle::<4, _>(reader), 10);
+        let reader = Cursor::new("zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw");
+        assert_eq!(solve_puzzle::<4, _>(reader), 11);
+    }
+
+    #[test]
+    fn second_with_additional_examples() {
+        let reader = Cursor::new("bvwbjplbgvbhsrlpgdmjqwftvncz");
+        assert_eq!(solve_puzzle::<14, _>(reader), 23);
+        let reader = Cursor::new("nppdvjthqldpwncqszvftbrmjlhg");
+        assert_eq!(solve_puzzle::<14, _>(reader), 23);
+        let reader = Cursor::new("nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg");
+        assert_eq!(solve_puzzle::<14, _>(reader), 29);
+        let reader = Cursor::new("zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw");
+        assert_eq!(solve_puzzle::<14, _>(reader), 26);
+    }
 }