Kth common ancestor in BST

class Solution {
    public int kthCommonAncestor(Node root, int k, int x, int y) {
        Node LCA=lca(root,x,y);
        ArrayList<Integer> al=new ArrayList<>();
        search(root, LCA, al);
        return (al.size()-k<0) ? -1 : al.get(al.size()-k);
    }
    
    void search(Node root, Node x, ArrayList<Integer> al){
        while(root!=null){
            al.add(root.data);
            if(root.data == x.data){
                return;
            }
            if(root.data<x.data){
                root=root.right;
            }else{
                root=root.left;
            }
        }
    }
    
    Node lca(Node root, int n1, int n2){
        while(root!=null){
            if(root.data>n1 && root.data>n2){
                root=root.left;
            }
            else if(root.data<n1 && root.data<n2){
                root=root.right;
            }
            else break;
        }
        return root;
    }
}