diff --git a/day06/input.txt b/day06/input.txt
new file mode 100644
index 0000000..f801dd1
--- /dev/null
+++ b/day06/input.txt
@@ -0,0 +1 @@
+pfptpztzfznzzznszzfgzgqgbgzgmzggwlwnlngnddjttzwtwmttlrrlqqzczpzhppmjmnjnfjnjjjprpfpnfpnpznzbbnwbbdsbswwwwszzzcmcttbftffczctztffppcvccbdbhbtbcbhbrbnrbrzbztbblvlvqvcqvcvcrcprrmffhfwfjwjrjtttvqqsttcwtthwthhqssbbqhhcbhbhqqwsqspqspprbrsrmmvhvvlsvspvpddbvdbdhhgshggfbgbrggzszsnshsvhsvhhnfnhfnhhbzzthtstdssdsrdsrdrtddsrdrcrgcgdcggdbbtgbgzbzwwnlngggspggspspjjfqflqqttjbbnffszfzjjlwjwhjwjccpllzztrzttdpdbbcnntwnnctnnrrgbrbvbccvzvlvnllvrvnnvmmtrmrddjdqdrqrmmvssgllsjsrrwggvcccgwwgddzldzldzdttqrrtggdngdgfdgfgzztdtthrttszzgjglldzdhdphppjfjfzfpfsflfggpwwwjdjssqdqmdmdpmmvbvfvpfpfwfpwfppbgbwgbbpmpwpzplpjpttnwnlnppcvchhmwwmllwppwspwspswpphhdhfhccwpcplpzzjwjssfrsssgnglnglnglngncgcvvpddrcrjrssznnjllslrlmllglpggwhhllzqzssvtsvvbpphpthphdhphnhdhdqdbbmcmqcmcmddtwtqqsbbzddtzdzrzmmfccdttlvljlffzczmzrrtzzrbrllfnfmfnnrcnnctcnnncbcrbccwcnwcnnrbnrrpnprrtwwvcwchwwcbwwwnpnvvgtvvqmvvhttrnnvjjtwtfwtwrrbpbmbmzmpphwphwwqwgwlwclwccjvccsllhhrtrstthvvfjjcvcdcbdcbczcttjbttwtvvvzjzgzwgwjjsnnvrrlbrrvnvdvhvchvvglvvpssdbsszddsqsspvpbpjjgghvvlwvlvggpjjmcjmmmhjmmrgrsgrsggchhcmmqsmsttlslqqmjjbpbrrcnrnbbvqvsvtvftvtmmqzzsnscsffnrnmrmnnszsllsrrrzrszsbbchccsrsmshhzrhrrdlrrjfmlrfhvqqvmpbrntgcqqsqvjmtctflbffddfbsjvzsfdwblprszhfvltwtcfsbdlwjgsmlcrvgstjqtrtnqzbmrmgqnscqjdfnbppcdgcsstwdmdvphsqmrfmzwntjgjjvcdgbhfjqlzglgjdsdlhwwrmfqcfsvhwwfmvprpnmjppvwzjwmddtndspzqjqrpbpnrjfwqfvbtqrgngcbjvhnfbtslcpppbsfhbcmwgpccftwhnbvdrzqdtwnrtjcdlnlmhvlzvljwrzgtfjrpgzjvggtpsvcdgtsvhdzvtfbwmnptfmllgcvfmmgvpbrgnhcnpwltqmjmltsbpzmfrttsmjqwhncvtqrsmcpsnrqzmwftbltllbhzhdfzmfgbvdtgwpvngsffjmwhfhmccfrjgqcqngzlnqvsgrcdzbsmjbmflwvhjldlrdvjrmgvjvpcczdhczpbtwphvhqmhcnljbwnzqwmbctffmctlcmhzcnvprdhtzdvgbhlnnjqzcwcsrgzjjlszssnplwqjlczvftmnbnmdpbjnctnslhgsjswqjwvprdstvbstlnnwwgvsffwmprjrlfccmtgvqbghvhcngwwtzwbwcdmrfstwhtfghgvzbfgtwjglcllwrhgdzptvrrbdhbscjhmtswshjmrsbpzstwmhrwwwncbbmjnjjlzrpdrzfvstbltszvlhcqbcpgbwtzzslsrljmhmtlcvzdbszvnjhrswrjrmfpsfpplwlrsnrpnjngmhwpwqcmtslhbmlsmjhcgmzznftmhvtmzlvmcwnbqtcntqghrqcsztsgzrnmrlvrnhtpmstdflpztmwltvgppttfwhhzzgrffjchswhbljvcjwvvnqnvdvjpsclhwsrtczvjmtcsnwvnwtdllphmrthddfvcjwvggqltmhglllmqzjsbjwgdqwzzmjnrmpbqplgzjgzcdqmtsntprdwwjwthcbsghqqspszndgqdmlzdlzwfcghtbhcqpbpmnfgqzmhtnttvjttvzhllsjvmmcmmppcgssjhnzqwpzdbtmrzsfbvgmgbtbwjrzvdlmgjpzltfmcclpltsszpqbllrwbwsnbhhvfwphrcpdvbjhgmgpphrdpcmjvfsjzrqldlqthwsztzcgttdnzcsbnszcsvmcspddlmwjttggdmlpqrdrfmwfzpdbnrwtmwssvbwtmzhndmhzwtlgdwpbrzghmlbszswqlpzldbvswjgtvjvmtjwdggfsbggbwhpwjdmflhmsgtbzrtbvlpqqmpcrbhflnfmwwsvdsgnnznfrqhqgqfgdfzcdqrtdftsntpbcclhncqjjwvszmssswnscwjlpfvdvltgcmqqttnfvbptbbmlrvrwwfbwwbvlrdrfmscqwdvdjgdrghwfjsttvwngzttzzsmzqnvzdfsvrbrcwtmmjdvnzjzdsnzgtszzcwdphnjmspmdsrqwgdwlzrgghcchpbltmwnjrbhqhzdqqmbrpggjjwnqfnnsqsfzbwqjsfprvrvfwbqvhgpjvqzplnhtqszqrtsvtbptfvzmvjhshbtmqbmqrrwplzphvdvhttlmftdwltqssstzlvnslzhnmjdlsbdprbgpjvcdtcfchzqqqcnngbrmntjwfbvcdcfgbcpnvcbbcvhqfzpsmgbcvrqvjlqlqnvvzdgphfpgtrpbbwztvqjgdpnpwbffdgqzmqvgblwzmdrhwdprhcqppcggrldhcdztnhspclfcwttnqslnzvvshcwgfztvscvztdrprvnlmfsgcpfdmfjgblnhrbsmjrjdzjwvwmlllvscsvfqvhdsdljrqphcvvtcttbwvnwwzwshdcfdqnjszltmddzjgmqgvpjzpzssrmfsrgjhvqtlhsfnndnqhpbcnltmdvlhfwqcmwnqbhsfqqwnfnnfjjbsqmcdrrvlfztdprnmjfhlvcdbjtczbrpljmpcwvchdwrqbwggjnrlhcdgzfwjzzjgfnbpwbpvswqdpcrthwfcffgztrjqntczfcbsrrtrjrwgbbgjshtzvjjlqqtsbgmpsttqjqwgmmbzhshqvvrcgbdsqmtqlrgjbnvbrpzdrgqnzstfdcvdnjhcnjblmsqtfvstlptgrczhbgpllpqwfdmthgjlltmlnltzpvjvjfgtrzslsptlfplgrgpjsbhbbbwlljfdjnhqcndlprfbwpvddndpnqwqccgbqmwlrffpzjpqclwcrgjgljwzpppwltcwdqdchghfnwbhrjndjsvlqnnmlrjfgfpnvgmlhbgnhnztpjzdmltfmjtzclsbspvhfngtjmzwrwmprdfplzzwfrdnbmbgvjlczcdvmpfmtqmzjrpfhjwwzmtnzmptwnhtlbndcpshqrqqrpccqpnvnqqdprvccmdmrsbptdhrhlpcptgfsfwphfpvbcrlnbrtgwcpgjclhhvpjhcwcgghlzbmpbswgtzqhmlwdfrrdfvnbhlqhvhnfjfndlqgrvhwnnnccvgdfqtwlmbwcpdtgscfpvmbdtcdmmgqrfjvnhngqsdtzhlbjwrrcrjfswwrgbhznlwhcjlsfprbqqcqmbdjhgjmmtqmjpldgqvptqcwjmlrjtjwdfbbvhpsnmfvdwnrntqzhfgfmrtgwgddpqvvdjqvrdwdwrsbjlbrmrjjbbpjpqgsjdzfjcrsnbmtmrstcrztzhgswgghwbfltdsvrcqvvjtmjwznnnwtsmshvbbpzwltrjpmbgsbqwphmwlhgpltsgjmgbdfrlhcbfjnvpvdwzccgdhswtgplcqnsjdwfbhbbpssvfrjbzmcphzjdncjgsvrcrplhqpnwdgfvrjqgfshdwrqjdvjmggtnnghqrccgddnzndcgpgpghtvrpwftfpttvgwqqcjbvnmqzlshdrdj
diff --git a/day06/inputdemo.txt b/day06/inputdemo.txt
new file mode 100644
index 0000000..19fe247
--- /dev/null
+++ b/day06/inputdemo.txt
@@ -0,0 +1 @@
+bvwbjplbgvbhsrlpgdmjqwftvncz
diff --git a/day06/main.lisp b/day06/main.lisp
new file mode 100644
index 0000000..83485c1
--- /dev/null
+++ b/day06/main.lisp
@@ -0,0 +1,20 @@
+(defun string-to-list (s)
+  (assert (stringp s) (s) "~s :questa non e una stringa")
+  (coerce s 'list))
+
+(defun unique-string (str)
+  (concatenate 'string (remove-duplicates (string-to-list str))))
+
+(defun unique-sequence (str n)
+  (if (= (length (unique-string (subseq str 0 n))) n)
+      (subseq str 0 n)
+      (unique-sequence (subseq str 1) n)))
+
+(defun part1 (str)
+  (+ 4 (search (unique-sequence str 4) str)))
+
+(let ((in (open "input.txt" :if-does-not-exist nil)))
+  (when in
+    (print (part1 (read-line in)))
+    (close in)))
+