diff --git a/2022/Cargo.lock b/2022/Cargo.lock
index 4eabd40..000c647 100644
--- a/2022/Cargo.lock
+++ b/2022/Cargo.lock
@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
 [[package]]
 name = "memchr"
 version = "2.5.0"
@@ -29,4 +35,14 @@ name = "problems"
 version = "0.1.0"
 dependencies = [
  "nom",
+ "substring",
+]
+
+[[package]]
+name = "substring"
+version = "1.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42ee6433ecef213b2e72f587ef64a2f5943e7cd16fbd82dbe8bc07486c534c86"
+dependencies = [
+ "autocfg",
 ]
diff --git a/2022/Cargo.toml b/2022/Cargo.toml
index fb3d37e..d8c9737 100644
--- a/2022/Cargo.toml
+++ b/2022/Cargo.toml
@@ -6,4 +6,5 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-nom = { version = "7" }
+nom =       { version = "7" }
+substring = { version = "1" }
diff --git a/2022/data/day6.txt b/2022/data/day6.txt
new file mode 100644
index 0000000..86395e5
--- /dev/null
+++ b/2022/data/day6.txt
@@ -0,0 +1 @@
+tnmmpfmfzmmnsmsjmjjbvvhnhzzfmmgpmgpgbgnnwffjhffzqqmzzbnbssrqqrnnhsnngsszsqzszhzfhzfzwzfzrrmhmghgwhhjjqwqttwhttjllrtrtzzcfzfgzznfznfzfnnbddvmvzmmfsmfsmfffhlfldlqqrnrznnhmmgqqzhhmjhmhppqbpbbngnlldvvdqvvrtrdrtrnttnppfllrbbrprpnpdplpmllhwwddqpdprddzzfccqpcqpcpcbbdhdjdjwjcwcctdcttzgzmmscmsmdmttwhwzhhnjhnhlhvhlvlglpgpmmjmgmrgrddmwddjfftfwflfslffqtfqttpftppflfmmhvhvcvbvhbhggpbgbppvdpvpvfppbwwsnnhphllbdbnbvbmvvzffvsffdldmlmtmccnlnbnjbnjnhhbfhhgzzlwlfflzffdccggdcgcjjhffjfgfgcczjccvwcvvqgvvqvllqzqmqllhjjqnqggttsdddjgdjgjzzrgrfrbrssrgrgdgrgbbssmdsdfddsndnsdnsdnnmqqsspqqmrqqpmmsjmmszzqvqrvrzznnjdndtntfnttgtctqtwwnwswrrthrttsdttlhlvvdzzgqgttnppjpljplpgpvgvqqvppzmmqggtjgtgstslltjltjjgcjcmjmsshvvtppgmmlslqqshqshsllbggfpgffdsdgssncchctcwwtllgqlqblqlqvvmsvmmwnnzppqllsttgmttftvfvjjrzzswzzjvzjzljjchcshcscbbrdbrbcrrnvvtctntvtvbvjvqjqggsrspsprrbgghdghhmwwldldzdttrvrnrfftqtftrrdsszlzvvbtbffftzzrzqrrhjhghhwbhhsjsfsttdjdjnjhjmjpmplplrrdjdcdjdbjblllbqlqdlqlpqptppdhhqmqfqhqhchwwqjqfjqfqhqshsmswsbbvssdspdpsdssstntltrrgnnmttgmmsjjrlrnlrnrnwrwfwlfltlzllcjcmjcjpjhphcpcwppmvmjjzbzvbbfnfcflfddntddbmmmhnnsrnrrvdvnvcvwvcwvwrrqwqccqmmswmmjrjmmwjmjfjhwrtbjzdvlgrjmvzfmhcqsncvlhzzncjlbvcwrdwjmqjcnptqslvfzpsvltgzsvjdsjrppdrmqrbqwhddfhnftfblspsrhtdtjwdnhbcbtlwlvccsfscvczzrrqmwbwbdmwgzqntvflppqvppwrhnvtlsbzqglhsfdgssqzdtjdpwrrhbnbtwhhnmnlwfwlqffjjrndbpwwsvdrhddbjnnqzmtpvvtwbcpndjzlhcfrrdvmljswjzvmfqcdsgqwclqshwrmblszdvsnrpdgnllmlchzdjlrrpndmmgddjqgjqrhwfbwddqdfbvptrmzhtsqfsfswpnvmtswqprjhbzvntgrlzthhnqbtpplqpvcfnpgdtbhqbhflltbbtmmhcwztslmpznttmssclhmnbsbrwlblrbsdfmnpqbwwmsncvzmpqwhzjgcgdrzvglgdtswmstdhrprdjfmqtjlmplbjtzcgnrwpdvpfjjfwjfnnpmdtwtqsgfndngsbmcwjtglqwtfrclbczfcmjtgcwszhzrbcphrhwmhcwghjznzthnwpljjltdlvqtffsrbmwcsvrdmqqggbznnlzbbqtgspqvnjpbdhtzmgttrcwwszwpgdrcnfqtgrgqdrctlzwtdwqppbhnwgldnqltznnfpbfqtgmmwpcqnndbgmrrtgtvnmlfcwsldchjnnqfrhpzwtclrzftsqllgvpqbgmfjdhqjttwcvbpvfqsvhbhhtwnqnbgndbtzhcvgglbhghbzrbrmdllmgfgttqmhtdnwrpwllhnghrjctrbzrcpnjnctvmrlpjhftnfbczrjrnnbqplplcrbngbhvmmvcffmgvbhjzbhcmtwmwgmjmwjvvlqfldswpntjnsjvmdlbzqqlgbwspwvmnwtwjbczmwplrhmjgsppnmtwmvsfwnsgddgwqcvpftcpzrhpldnwmcjgtjmljjbcmjcqdbwczndnjnjgrmtjrqnnjndzqdqpcgdqptdbrqftnwrgqmrzrvsfmmmbpltlncvtgrjfjmvtgwqphczwjhdrdwtfvgztbhrndvpcbgfjfvmrrljwrvcrtdmtjndfnwgcnfrzgsnjpztbwwsbvqfnpjctgrhsflhnzbbsfqbnmtnvrmjzsbjfndvttpvpfjhqntflgbfnzcclcwmhbsgqfjdcgsvrhtstspfzgvgglgddqmclsmzgzgtncdsfmwdvtcsgwvbzjvclwppqdjgfcrcbzcwbdhrnssjbmnmfmwthdrnmlfhqlddwqrdhsdvdcsmcgjsgcmpnhlbnqftpdjswtmpbznlcrhtswgnmwjcdfmljdngzfsmlzjjnzmfzshmztdbdmcqwmlvcrzgpmbjqcghclwvdbrhgvwqchnndftnrtptmctdlhmfjvpzrpccddfpcdwmzqfhnsqzrvwblzfhcjdcjfctczwqrcbjnrpdcbbnsgnlvqqmnsfgsqschjlbzhhsrbvdbfrhvsgrlzwncgwpdbvmblgzbwbcbgqfwmdmgcrbbjfcvmqgztqpptdhwmvmsdqwplpgcjzgqzdrftzhqbltvhrmlrfffcgfpqzwrrbbtlsjgmtbjvtnmhwdpjptjwfwgjgvbfqwmflrrqzlzdcmtlnptdrpcpdnswcfscnndnrfbgwvvncdjgsdpbwptdtvrqlmrhmvvcwblhhzbjdpsbszhrftfbcgwhwrgglnjzqdhcqnvlhgqjhnddvrslhntssptsbhmqwwqqnbvfmcbgpvgjbrttnvlljdbtfplgmbwtcbcdtqdpqqdvhbmpmtszwpzblcfrtznhhtcljtdlhjdbnlhvwgjsmgvrslrfwnmzwlstpgltvrgnpdqztvfnvdhdtwwqdfsmtpbpdclsbnwcgjzchjcsjmvhbjshmjjlpgdzcgbmmchwmcsddsvhsnpqtcpnhqnbvwgwqhtjbqncgwwftnrzsbsjtvqmjzqvvncmncwflcfpcjqgdtbsmjzzsdjfvhnqbgjhmfgjghwscthbfmbndltbqzwpqtmrswvprpmgwqnqpfnmffrpdlpfqmhrthppzvzwbrtjvwvjndsqdlqtbpqwfcttggnjmcqqnmjwfhfjgcvlnmtlgbdvmctzlwbfgnflwtsflgnfbnfbhhdgjctzvvmrhdsmvmmtnqwtszmqcpsbrqrgjfrzctcbzmtdlhwjtfdqbtthdnqcrpwrhcrvjstbhpltvgmvpmvfjstgzjsgzprzcqzqztvvdcnrrqwrhddcrhhncdrlwzwqlnbbzcfmqtnwgfdscmrbwnbldlfrqchzdnlnmwncgrzdclnvcvplgwjsbzmbnnsdrsfhrlssvncnwmcrjdjbjpdtrrvlnbjvspfqbwdpcnnpjzfnmbhcdhlmdgbpvbzmfltzstnznfctcdzhbfsvnfbsjqzmwfllhtrsfghlrpjgrgzgchlwrdmqzbrncsvnwhfqmwjbnvjctzphcsftqsbmwntgvjqhhvwndvmfmjhhhmfdvrlhpvzmmhrbhbddqbdmgqqsvddsswmzqcjmvhztfqpchzpwhdshzjlmbmnsgzqhbnmrshwvtmgmgndtddpfwsjrrjdhncdhtlczdvlbvqplttnzrblthlcffdtfsdtpwzdgbldvnsttvpzmbgnqddrszftcpwrgmfzhjjvghpntmzcttcsnrjnfpqzqqqljhzlrpgwngllqjwnwfcsphqplgbzmfqfgbfsqpsrntszqbcqnhctsnbfshmlbwfflrwwsjwqwfqlgnftdwmctmclwjhjhbsspqldlshbmpbgrftpnbpsqldhrrbdqwfwvfhclrlfdjfmzgmptdjdcsplcspznfjrfhtsjndwpslrdgnllllwqjgznrhswfssdlvdpmwwgmstqbhfmdhtzvzzvhwzbrrvvsl
diff --git a/2022/src/day6.rs b/2022/src/day6.rs
new file mode 100644
index 0000000..84a4161
--- /dev/null
+++ b/2022/src/day6.rs
@@ -0,0 +1,68 @@
+use std::collections::HashSet;
+use substring::Substring;
+
+const INPUT: &str = include_str!("../data/day6.txt");
+
+pub fn part1() -> String {
+    format!("{:?}", start_of_packet(INPUT))
+}
+
+pub fn part2() -> String {
+    format!("{:?}", start_of_message(INPUT))
+}
+
+fn start_of_packet(input: &str) -> Option<usize> {
+    first_unique_window(input, 4)
+}
+
+fn start_of_message(input: &str) -> Option<usize> {
+    first_unique_window(input, 14)
+}
+
+fn first_unique_window(input: &str, window_size: usize) -> Option<usize> {
+    for window_idx in 0..(input.len() - window_size) {
+        let window = input
+            .substring(window_idx, window_idx + window_size)
+            .chars()
+            .collect::<HashSet<char>>();
+        if window.len() == window_size {
+            return Some(window_idx + window_size);
+        }
+    }
+    None
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn it_finds_start_of_packet() {
+        assert_eq!(start_of_packet("mjqjpqmgbljsphdztnvjfqwrcgsmlb"), Some(7));
+        assert_eq!(start_of_packet("bvwbjplbgvbhsrlpgdmjqwftvncz"), Some(5));
+        assert_eq!(start_of_packet("nppdvjthqldpwncqszvftbrmjlhg"), Some(6));
+        assert_eq!(
+            start_of_packet("nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg"),
+            Some(10)
+        );
+        assert_eq!(
+            start_of_packet("zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw"),
+            Some(11)
+        );
+    }
+
+    #[test]
+    fn it_finds_start_of_message() {
+        assert_eq!(start_of_message("mjqjpqmgbljsphdztnvjfqwrcgsmlb"), Some(19));
+        assert_eq!(start_of_message("bvwbjplbgvbhsrlpgdmjqwftvncz"), Some(23));
+        assert_eq!(start_of_message("nppdvjthqldpwncqszvftbrmjlhg"), Some(23));
+        assert_eq!(
+            start_of_message("nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg"),
+            Some(29)
+        );
+        assert_eq!(
+            start_of_message("zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw"),
+            Some(26)
+        );
+    }
+}
diff --git a/2022/src/main.rs b/2022/src/main.rs
index 3d36ba3..077dac4 100644
--- a/2022/src/main.rs
+++ b/2022/src/main.rs
@@ -3,6 +3,7 @@ mod day2;
 mod day3;
 mod day4;
 mod day5;
+mod day6;
 
 fn main() {
     let day = std::env::args().skip(1).next();
@@ -18,6 +19,8 @@ fn main() {
         Some("4b") => day4::part2(),
         Some("5a") => day5::part1(),
         Some("5b") => day5::part2(),
+        Some("6a") => day6::part1(),
+        Some("6b") => day6::part2(),
         _ => panic!("unrecognized day"),
     };