diff --git a/logic-exercises/exercise-day-4/longestCommon.js b/logic-exercises/exercise-day-4/longestCommon.js
new file mode 100644
index 0000000..dff6041
--- /dev/null
+++ b/logic-exercises/exercise-day-4/longestCommon.js
@@ -0,0 +1,20 @@
+function longestCommon(strs) {
+    if (strs.length === 0)
+        return "";
+    var commonPrefix = "";
+    for (var i = 0; i < strs[0].length; i++) {
+        var currentChar = strs[0][i];
+        var areAllCharsSame = true;
+        for (var j = 0; j < strs.length; j++) {
+            if (strs[j][i] !== currentChar) {
+                return commonPrefix;
+            }
+        }
+        if (currentChar) {
+            commonPrefix += currentChar;
+        }
+    }
+    return commonPrefix;
+}
+console.log(longestCommon(["Palmeiras", "Palermo"]));
+console.log(longestCommon(["porco", "gamba"]));
diff --git a/logic-exercises/exercise-day-4/longestCommon.test.ts b/logic-exercises/exercise-day-4/longestCommon.test.ts
new file mode 100644
index 0000000..e69de29
diff --git a/logic-exercises/exercise-day-4/longestCommon.ts b/logic-exercises/exercise-day-4/longestCommon.ts
new file mode 100644
index 0000000..2db8ec8
--- /dev/null
+++ b/logic-exercises/exercise-day-4/longestCommon.ts
@@ -0,0 +1,24 @@
+function longestCommon(strs) {
+    
+    if (strs.length === 0) return ""
+    
+    let commonPrefix = ""
+    for (let i = 0; i < strs[0].length; i++) {
+        let currentChar = strs[0][i]
+        let areAllCharsSame = true
+        
+        for (let j = 0; j < strs.length; j++) {
+            if(strs[j][i] !== currentChar) {
+                return commonPrefix
+            }
+        }
+        
+        if(currentChar) {
+            commonPrefix += currentChar
+        }
+    }
+    return commonPrefix
+}
+
+console.log(longestCommon(["Palmeiras", "Palermo"]))
+console.log(longestCommon(["porco", "gamba"]))
\ No newline at end of file
diff --git a/logic-exercises/exercise-day-4/package.json b/logic-exercises/exercise-day-4/package.json
new file mode 100644
index 0000000..c1aaf1a
--- /dev/null
+++ b/logic-exercises/exercise-day-4/package.json
@@ -0,0 +1,13 @@
+{
+  "name": "exercise-day-4",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "start":"clear && tsc --outFile longestCommon.js longestCommon.ts && node longestCommon.js",
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC"
+}