diff --git a/index.js b/index.js
index 0f4b28b..7726054 100644
--- a/index.js
+++ b/index.js
@@ -1,17 +1,46 @@
 class SortedList {
-  constructor() {}
+  constructor() {
+    this.items = [];
+    this.length = 0; 
+  }
 
-  add(item) {}
+  add(item) {
+    this.items.push(item); 
+    this.items.sort((a, b) => a - b); 
+    this.length = this.items.length; 
+  }
 
-  get(pos) {}
+  get(pos) {
+    if (pos >= this.length || pos < 0) {
+      throw new Error('OutOfBounds'); 
+    }
+    return this.items[pos]; 
+  }
 
-  max() {}
+  max() {
+    if (this.length === 0) {
+      throw new Error('EmptySortedList'); 
+    }
+    return Math.max(...this.items); 
+  }
 
-  min() {}
+  min() {
+    if (this.length === 0) {
+      throw new Error('EmptySortedList'); 
+    }
+    return Math.min(...this.items); 
+  }
 
-  sum() {}
+  sum() {
+    return this.items.reduce((acc, curr) => acc + curr, 0); 
+  }
 
-  avg() {}
+  avg() {
+    if (this.length === 0) {
+      throw new Error('EmptySortedList');
+    }
+    return this.sum() / this.length; 
+  }
 }
 
-module.exports = SortedList;
+module.exports = SortedList; 
diff --git a/package.json b/package.json
index 2940292..d36e941 100644
--- a/package.json
+++ b/package.json
@@ -12,5 +12,8 @@
     "intro"
   ],
   "author": "supoort@rootlearn.com",
-  "license": "MIT"
+  "license": "MIT",
+  "dependencies": {
+    "mocha": "^10.7.3"
+  }
 }