diff --git a/bin/d6/dune b/bin/d6/dune
new file mode 100644
index 0000000..aee3d40
--- /dev/null
+++ b/bin/d6/dune
@@ -0,0 +1,4 @@
+(executable
+ (public_name d6)
+ (name main)
+ (libraries utils))
diff --git a/bin/d6/input.txt b/bin/d6/input.txt
new file mode 100644
index 0000000..f86c568
--- /dev/null
+++ b/bin/d6/input.txt
@@ -0,0 +1 @@
+hrbbjllllspssblslvvrdrbbpbbmcccfppvbbwvbbmrmjrjrfrgfgbffgfqfqlltlwttscsncscchssrppffvwwvvpnnwwwpvwvhhnvhhbttvzzdlzdlzzwmmjhhznnjdnnnqddbtdbdbsdsmdsdrrdpdwpdppgcgqgcctftsfszslljbljbjwbwbnwnqqrnnztntmtrmmzwzdwzwgwwwjhjsjgjtjjhpjhhppqzqdqffrvrtvvsmmgwmgwgbbclltctptzpzhpzptzppcfpcfftflfzftztddzgzmmfsmsrmmsstttvbvmbvvsmsqmqlldjdtthwtwbwggrzzjrzrcctffsshqshhpthhlnhlhqhdqqrwrmmcttpfttzfzgzdgdzzwrrtsrrsnrnccrbbsssbpbjjvzzwlwtwjwsjwjggzqgzzrsszzjnzjzwjzzcrzczncnqqztzfzhfhvvtjvjdvjjmrjrppvzppczpczcggshghvhnhhsrsnsdszzdpzpzlpzzhwwmnwmwmcwwfnwfwjjcbcncllcsllqdqzzhqhmqmbbjvjjwwcjjpnpllzfzddtmtccqrcrtrwrpphpmpplslmltthnnvhhvrvbblhhrrdqqmbqqgtqggdgcdcvvsbsswvvpggbbtftlflglzlmlbbfhhrshswhshffhhdnnrfrvrmrnrprrmfmpmnpnfnggvvcncdcrczrzccpmmssrbbdjdtdrdwrrwhrrvrtvvszvvwvzzmhhjhhwlhlqlvlttzftztdtstftrfrdddmtmzzsqzqvvpdpdcpcncnrrtntznzrzgznztnznhhsqqnrqrhhlzhzthhfddrzdrrqmqggcmmllnjjvwwjccfjfqfcfzccwvcwvcvjcjtjtnnqsqmqrmrzrszrszzfwfggnmmcdmdjmmhwwgfwfnwnlwwcffsrffvnvbvnvwnwgnwnmmbzbmbpplmplpspzpmzpzdzgzrzrtrjrbbppwvwgwmggqwgghqqshhcwcqwcqcfcbbnsnrrtztzrtrvtvhthzhmmrqqrwqqsjqjcctgtwthhqmmnffmgmdgdlgljjhwjwggrqqfrqqjvqvhqqgsqsgsttmrrbprbppmjppslpsllvlfvlvrvhvtqmrjcdzwsbzfmgmwmwqwhztqrsdzhqjqvbjbntnbndflthljcczdmmhszfgsplrtlqnfzbrlqngwdqtfwcmrdjrsmdpmjmqwrbwfjzwnvqhfmlqtvvnlfzbfccwslqpbzzjccbvrzhghqwtvqgwrmsfzqnmnqqjsjtpcmngpqgllfsnpqtjjbqcdppnsmtwrslnrbqtwvnbctzvwfmgctscmzjbqqgqdwbpzmrdwgfcjzftzgmfcjhchbnmnqnrgtqngwrmncjvptqqdtjtgtpzzdrfsdgmwlwrjnqldbwrqjrhwcczlzvlhpgrnwzhbwjnpthggczfgtrjnzvnlfdfbwcnzfbwlwlmgnnjnpvhbhqgnzhqsnmvbcftsmrcgpvnnnmgnrvpbzlpwnbwpzmwpgqvbfgjwfrjqnvvgmqwwcfddqmdznmfhpjcfgptqdqwmplrglbwlmsqzjshrlhflcjvptgrcfhjfgqmlfzrtphpbvcqzwpcnwljjdlmqzhcctqshdngrgtlfsrfccdtlvmqcdgnpcvphdsrpzfzwclvsqcpzqlfvvqzggdhpfzdvhshglvfzfmcllrdfjfsjtngjgddcpqnlmrnplwtlvwdvzftltnsnspcdztgqhlhvvbnwvnmhscfnqbngpvprzfrjcmfpfzfftrlnwgllhnjndpjdrwcgqpcgcqngnbfzlvzvhnqdjthflmwvppmbdssddmgsbgrqnpjzrjpzdddqgsdlmwnhhpjbthclvqhgrsnrbqgtnsjhncnzbhrdgftvbptrqssvsqfpqnddhmgwcrfqndqjsqgffmhdvqhjrdlmrlcqctqccprwlbqgqrwmtfhwmfjfqzdqbsdsjbtsvfvgbsrvqwnqqqqthpsqgcfslsqtnjwtsrcdcctggdghrjwpbfccrtwgszwbrsjswmjmjbcqrsgbcfsdjzsbjnnssnddnnvwgftlrqvphnqcgjszscrlhhjnljlqcjqtqfwbmdmrgdlcqqwmbsmsdhpplvlfglqwspbfptlbzqjwhqmfvzvsvpjclcdzsbvntmhdqdvhghcmmflpjbglsghbswdshtsbdrgpsrsclrmfwwqbrgdjsqztgttqpwhnfhszlgbfpzhczsnwqflmshlgbrpmdzgpqwtsbssgfjbtrwbmztlwwfmsdgpgfgdjfdccwlfgztbcbqjvjtvslmddjplrswwcszspgplsrhrnwnmrrfbcgdmntcrlvnfqtwwcczsglrhtrfqnmhvgzjpmlplqvqhmnfgvzqcmzhqszgslvndqtqhvrbvbmclbcbjdswvcjrzgfdmdwnnlzlzqcffsrqdfmmpzfnmdsnqlpcrhzsdnsflblcjsfsgcnsspftjrlmdjsmfpqtmlgfvnlfnjscsgwzwvpjrvvclhsbqldlnmtglhbjfwlzmvrbvgtprfjbjhhnlqnbrswwlqtcgrjrltdrnfrjhrntllptlsbhqrwvdsfrlghtfcndznzjwcgmtdvffltgrdmljlqhdtmdvnfsfsrvdpmhlrrsttvqlwfptddwbpfrbclwwzmfpttmrmmqzjnbbnnfvzwmmcfshvrlbdbjzprftbqvdsghnnzwbjccpthdsvsdlgvphsgjdqjwsgmzqnqpqvgqjvwgjtzpmqqwnlwrwhqqjjclcbhjgpwhqdclwmqfmwbwmwwvcbhfznfhcfbprfcdqlbcttnvgnjwswcmpbrghtzgdbppbprffzjgvddzpwmdctrhnrfzdfhtmnfrsfdqvzcnrtncflhvldcndwqtvbggmwlzhchlcwtcbqcvlfhdwljgddwpvcfczvfqmphgtdsnsqwdpvvmwnwqjbrjwbdhhgtffphsdrvspsbgmfrmwmhnrgqdfppzgfpgmqjcsnglczgwhjthfhztzrlpgzjhcfrjpjvtjptptbvflftjtcfhmbwlhlbhvnjnbfmwjrgbvvhmdlncdgncgfjcnnpdljfcjsmsfscqpwsgcmlhhqmldsnjfrrqpghwncmgwgnjsdtvbhrbbnmpqjrrctqqnqzztmbqmdsgdvmmlwmbvprllzgntnmttrlzrttmjjlrwpwmtfznmwnsjmjhjdnsppfhcrjpzhjqzdtdbsjshfzzvrwvjbjbgtsfpgggbdztczwlhpmthfjdgsbrvlwmlrvgdrpjzccwmgpcnqqzmqdjqmwsrzwsmtmdjdhmjrwfwnzlmfnqtcgtslwtlnwhvmqntmglhntnsjlnmzfvfdztcfwmpchsrsdmqvqcwljzrmmssjvbmvvnmqlbsdwnrbmqctdtmfzlgfzpmjcnftgftvjpfbwwmzfdrrwjwcfwfcfmzbbnppgjrmbcvmvnjpdrzmvndvddtvshlnjjwgtsvnwtwnhcbfpnthpjlrhgrqccdgppjvdqjwqrfrrgnvhfwvjhnwhntnpmghphrtgqhwtbrqhqljfdjbgnlgmqqgfcqpqfhcpgspdbvlbfjvlrgmtjztwdzlrhqwwtcpdvsqgssjbjjgqlwbcctzzqvvmdzpfrmspmqhtzwgcfsslpnhpjfwqrrfbwbndrvhnnsjnlvlvqdsgwzjsrprhgtvsfbhbcpljdczbtdwzcnhzntrwcrjctmhtjfdlthznzmqblppzcqgpjhlzjrmcvpptfjjzltdhmvwphwlccscwrwfcqpqwwrzcmnltzdcfvtjrcvsqwtchrmdfzjmzjfhppjzbhglwqggzqqnspfmzrfwrqdqdrsdbsdhcgdqrrnjlwrqhfhpzjhrvjndqphndnnnbwhrjvqrrbvlhhbljjcwmfpvnhcszfshlsnczgtcfhjslbhzczdqdmdnvqdzhbmbpcnbntwgllfscrcwhfrgtfvftmwhbgfhjzjrbvvwc
diff --git a/bin/d6/main.ml b/bin/d6/main.ml
new file mode 100644
index 0000000..3301c6f
--- /dev/null
+++ b/bin/d6/main.ml
@@ -0,0 +1,21 @@
+let has_repeating_char s =
+    let chars = List.init (String.length s) (String.get s) in
+    let rec aux = function
+        | x :: xs -> List.exists (fun q -> q = x) xs || aux xs
+        | [] -> false
+    in aux chars
+
+exception NotFound
+
+let calculate_offset offset input =
+    let buf = String.sub input 0 offset in
+    let rec aux idx buf input =
+        if not (has_repeating_char buf) then idx + offset - 1
+        else if idx + offset = String.length input then raise NotFound
+        else aux (idx + 1) (String.sub input idx offset) input in
+    aux 1 buf input
+
+let input = Utils.read_file "bin/d6/input.txt" |> List.hd ;;
+"\n1: " ^ (string_of_int (calculate_offset 4 input)) ^
+"\n2: " ^ (string_of_int ((calculate_offset 14 input)))
+    |> print_endline