diff --git a/README.md b/README.md
index da57339..3bbe820 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,5 @@
+# Advent of Code 2022 - Assignment6_javascript
 This repository contains answers to the assignments of Advent of Coding 2022
+
+## References
+- https://stackoverflow.com/questions/28207610/checking-if-the-characters-in-a-string-are-all-unique
\ No newline at end of file
diff --git a/index.html b/index.html
index 5cf1ba4..794716f 100644
--- a/index.html
+++ b/index.html
@@ -8,7 +8,9 @@
   <body>
     <p>Assignment:</p>
     <textarea rows="15" cols="50" id="assignment"></textarea>
-
+    <input type="checkbox" id="algorithm" />
+    <label for="algorithm">Search for message marker?</label>
+    
     <p>Answer:</p>
     <div id="answer">Provide input first</div>
     <script src="script.js"></script>
diff --git a/script.js b/script.js
index a6e2848..d89ce30 100644
--- a/script.js
+++ b/script.js
@@ -1,12 +1,16 @@
 const ASSIGNMENT = 'assignment';
 const ANSWER = 'answer';
+const ALGORITHM_CHECKBOX = 'algorithm';
+const MARKER_DISTINCT_CHARACTERS = 4;
+const MESSAGE_DISTINCT_CHARACTERS = 14;
 const NEWLINE_CHARACTER = '\n';
 
 /**
  * Main function
  */
 window.onload = function() {
-    document.getElementById(ASSIGNMENT).addEventListener("input", calculateAnswer);
+  document.getElementById(ASSIGNMENT).addEventListener("input", calculateAnswer);
+  document.getElementById(ALGORITHM_CHECKBOX).addEventListener("click", calculateAnswer);
 }
 
 /**
@@ -15,7 +19,9 @@ window.onload = function() {
  */
 function calculateAnswer(event) {
   console.info("Calculating answer for input...");
-  let answer = algorithm(event.target.value);
+  let assignment = document.getElementById(ASSIGNMENT).value;
+  let distinctCharacters = (document.getElementById(ALGORITHM_CHECKBOX).checked)? MESSAGE_DISTINCT_CHARACTERS: MARKER_DISTINCT_CHARACTERS;
+  let answer = algorithm(assignment, distinctCharacters);
 
   document.getElementById(ANSWER).innerText = answer;
 }
@@ -25,9 +31,28 @@ function calculateAnswer(event) {
  * @param assignment the input from the assignment.
  * @return string the answer
  */
-function algorithm(assignment) {
-    let lines = assignment.trim().split(NEWLINE_CHARACTER);
-    console.info("Linecount:" + lines.length);
+function algorithm(assignment, distinctCharacters) {
+    let signal = assignment.trim();
+    let marker = assignment.substring(0,distinctCharacters);
 
-    // TODO: implement assignment
+    for(let i=distinctCharacters; i<signal.length; i++) {
+      if(containsDistinctCharacters(marker)) {
+        console.debug("Found marker after:" + i + " characters");
+        return "Marker found after processing: " + i + " characters.";
+      }
+
+      marker = marker.substring(1, distinctCharacters) + assignment[i];
+    }
+
+    return "No marker found.";
+}
+
+/**
+ * Check if string only contains distinct characters.
+ * @param String string the string to check
+ * @return true, if string contains only distinct characters
+ */
+function containsDistinctCharacters(string) {
+  console.debug("Check marker: " + string);
+  return new Set(string).size == string.length;
 }
\ No newline at end of file
diff --git a/style.css b/style.css
index f39a6bd..11e662f 100644
--- a/style.css
+++ b/style.css
@@ -6,6 +6,10 @@ body {
     font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
   }
   
+  textarea {
+    display: block;
+  }
+  
   #answer {
     color: purple
   }
