```js
function LinkedList() {
var length = 0;
var head = null;
var Node = function(element){
this.element = element;
this.next = null;
};
this.size = function(){
return length;
};
this.head = function(){
return head;
};
this.add = function(element){
var node = new Node(element);
if(head === null){
head = node;
} else {
currentNode = head;
while(currentNode.next){
currentNode = currentNode.next;
}
currentNode.next = node;
}
length++;
};
// Only change code below this line
// Only change code above this line
}
```
## Solution