Linked List 2:Find a node in LL (recursive)

public class Solution {
	public static int indexOfNRec(LinkedListNode<Integer> head, int n) {
       return  helper(head,0,n);
    }
    public static int helper(LinkedListNode<Integer> head,int index,int n){
        if(head==null)
            return -1;
        if(head.data==n)
            return index;
       int ans= helper(head.next,index+1,n);
      return ans;
	}
}