let rec countNodes = function
|Node(v,[]) -> 1
|Node(v,l) -> 1 + foldl (fun (b,x) -> b + countNodes(x))(0,l);;

(*10.*)
let rec numDosen = function
|Node(v,[]) -> 1
|Node(v,l) -> foldl (fun (b,x) -> b + numDosen(x))(0,l);;

(*11.*)
let rec extNode = function
|Node(v,[])-> [v]
|Node(v,l)-> foldl(fun (h,x) -> h @ extNode(x)) ([],l);;

let rec daftarDosen = function
|(Node(v,[]),n) -> []
|(Node(v,l),n) -> if n = v then quik(extNode(Node(v,l)),[]) else foldl(fun (h,x) -> h @ daftarDosen(x,n)) ([],l);;