View Compilation Error

0_0_28889337_23911\Main.java:38: 错误: 程序包org.smallnico.hdu.S1506.CartesianTree不存在
    public static int area(org.smallnico.hdu.S1506.CartesianTree.Node n) {
                                                                ^
0_0_28889337_23911\Main.java:43: 错误: 程序包org.smallnico.hdu.S1506.CartesianTree不存在
    public static int dfs(org.smallnico.hdu.S1506.CartesianTree.Node n, int count) {
                                                               ^
0_0_28889337_23911\Main.java:26: 错误: 程序包org.smallnico.hdu.S1506.CartesianTree不存在
            List<org.smallnico.hdu.S1506.CartesianTree.Node> nodes = t.getList();
                                                      ^
0_0_28889337_23911\Main.java:28: 错误: 程序包org.smallnico.hdu.S1506.CartesianTree不存在
            for(org.smallnico.hdu.S1506.CartesianTree.Node n: nodes) {
                                                     ^
0_0_28889337_23911\Main.java:82: 错误: 程序包S1506.CartesianTree不存在
            List<Node> list = new ArrayList<S1506.CartesianTree.Node>();
                                                               ^
5 个错误