import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;
/**
* Built using CHelper plug-in
* Actual solution is at the top
*/
public class power {
public static void main(String[] args) {
InputStream inputStream = System.in;
OutputStream outputStream = System.out;
InputReader in = new InputReader(inputStream);
PrintWriter out = new PrintWriter(outputStream);
powersol solver = new powersol();
solver.solve(1, in, out);
out.close();
}
static class powersol {
char[] s;
int[][] adj;
int ans = 0;
public void solve(int testNumber, InputReader in, PrintWriter out) {
int N = in.nextInt();
int[] U = new int[N - 1];
int[] V = new int[N - 1];
for (int i = 0; i < N - 1; i++) {
U[i] = in.nextInt() - 1;
V[i] = in.nextInt() - 1;
}
adj = DefaultTree.packU(N, U, V);
s = in.next().toCharArray();
dfs(0, 0);
out.println(ans);
}
int dfs(int n, int p) {
int mx = 0;
int tot = 0;
for (int e : adj[n]) {
if (e != p) {
int a = dfs(e, n);
mx = Math.max(mx, a);
tot += a;
}
}
ans = Math.max(ans, tot - (s[n] == '1' ? 1 : 0));
if (s[n] == '1') {
ans = Math.max(ans, mx + 1);
}
if (s[n] == '1') {
return Math.max(1, tot - 1);
}
return tot;
}
}
static class DefaultTree {
DefaultTree.Node[] tree;
int K;
int[][] lift;
int[] tin;
int[] tout;
public DefaultTree(int N) {
tree = new DefaultTree.Node[N];
K = (int) Math.ceil(Math.log(N) / Math.log(2)) + 1;
lift = new int[N][K];
tin = new int[N];
tout = new int[N];
for (int i = 0; i < N; i++) {
tree[i] = new DefaultTree.Node();
}
}
public static int[][] packU(int N, int[] from, int[] to) {
//undirected
int[][] adj = new int[N][];
int[] cntFrom = new int[N];
for (int i = 0; i < from.length; i++) {
cntFrom[from[i]]++;
cntFrom[to[i]]++;
}
for (int i = 0; i < N; i++) {
adj[i] = new int[cntFrom[i]];
}
for (int i = 0; i < from.length; i++) {
adj[from[i]][--cntFrom[from[i]]] = to[i];
adj[to[i]][--cntFrom[to[i]]] = from[i];
}
return adj;
}
static class Node {
}
}
static class InputReader {
public BufferedReader reader;
public StringTokenizer tokenizer;
public InputReader(InputStream stream) {
reader = new BufferedReader(new InputStreamReader(stream), 32768);
tokenizer = null;
}
public String next() {
while (tokenizer == null || !tokenizer.hasMoreTokens()) {
try {
tokenizer = new StringTokenizer(reader.readLine());
} catch (IOException e) {
throw new RuntimeException(e);
}
}
return tokenizer.nextToken();
}
public int nextInt() {
return Integer.parseInt(next());
}
}
}
