diff --git a/index.js b/index.js
index 0f4b28b..e6998a0 100644
--- a/index.js
+++ b/index.js
@@ -1,17 +1,47 @@
 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<0 || pos>=this.length){
+      throw new Error("OutOfBounds")
+    }
+    return this.items[pos]
+  }
 
-  max() {}
+  max() {
+    if(this.length===0){
+      throw new Error("EmptySortedList")
+    }
+    return this.items[this.length-1]
+  }
 
-  min() {}
+  min() {
+    if(this.length===0){
+      throw new Error("EmptySortedList")
+    }
+    return this.items[0]
+  }
 
-  sum() {}
+  sum() {
+    return this.items.reduce((acc,curr)=>acc+curr,0)
+  }
+
+  avg() {
+    if(this.length===0){
+      throw new Error('EmptySortedList')
+    }
+    return this.sum()/this.length
+  }
+  }
 
-  avg() {}
-}
 
 module.exports = SortedList;
diff --git a/package.json b/package.json
index 2940292..8f04c69 100644
--- a/package.json
+++ b/package.json
@@ -12,5 +12,8 @@
     "intro"
   ],
   "author": "supoort@rootlearn.com",
-  "license": "MIT"
+  "license": "MIT",
+  "dependencies": {
+    "mocha": "^10.4.0"
+  }
 }