data NTree= NilT |
    Node Int NTree NTree

sumTree :: NTree-> Int
sumTree NilT = 0
sumTree (Node n t1 t2) = n + sumTree t1 + sumTree t2


depth :: NTree-> Int
depth NilT  = 0
depth (Node n t1 t2) = 1 + max (depth t1) (depth t2)