public static void BFS_Visit(Vertex<Integer> u) {
Deque<Vertex<Integer>> q = new LinkedList<>();
q.add(u);
while (!q.isEmpty()) {
Vertex<Integer> v = q.poll();
v.setMarkState(Graph.VISIT_COLOR_GREY);
for (Edge<Integer> x : v.getOutgoingEdges()) {
Vertex<Integer> ver = x.getTo();
if (ver.getMarkState() == Graph.VISIT_COLOR_WHITE) {
if (ver.getData() != 0) ver.setData(v.getData() + 1);
ver.setParent(v);
q.add(ver);
}
}
v.setMarkState(Graph.VISIT_COLOR_BLACK);
}
}
public static void main(String[] args) throws IOException {
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
String[] input = in.readLine().split(" ");
int n = Integer.parseInt(input[0]);
int m = Integer.parseInt(input[1]);
Graph<Integer> g = new Graph<>();
input = in.readLine().split(" ");
int[] cats = new int[n + 1];
for (int i = 1; i <= n; i++) {
cats[i] = Integer.parseInt(input[i - 1]);
Vertex<Integer> v = new Vertex<>(Integer.toString(i), cats[i]);
g.addVertex(v);
}
for (int i = 1; i < n; i++) {
input = in.readLine().split(" ");
int x = Integer.parseInt(input[0]);
int y = Integer.parseInt(input[1]);
Vertex<Integer> from = g.findVertexByName(Integer.toString(x));
Vertex<Integer> to = g.findVertexByName(Integer.toString(y));
g.insertBiEdge(from, to, 0);
}
BFS_Visit(g.findVertexByName("1"));
int count = 0;
for (int i = 1; i <= n; i++) {
Vertex<Integer> vertex = g.findVertexByName(Integer.toString(i));
if (vertex.getOutgoingEdgeCount() == 1 && i != 1) {
int maxi = 0;
while (vertex.getParent() != null) {
maxi = Math.max(maxi, vertex.getData());
// System.out.print(vertex.getName() + " ");
vertex = vertex.getParent();
}
// System.out.println();
maxi = Math.max(maxi, vertex.getData());
if (maxi <= m) count++;
}
}
System.out.println(count);
}