// ¯\_(ツ)_/¯
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
#define all(x) (x).begin(),(x).end()
#define X first
#define Y second
#define sep ' '
#define endl '\n'
#define debug(x) cerr << #x << ": " << x << endl;
const ll MAXN = 1e6 + 10;
const ll INF = 1e9;
const ll MOD = 1e9 + 7; // 998244353; // 1e9 + 9;
int n, dp[MAXN], ans = 0;
bool B[MAXN];
vector<int> adj[MAXN];
void dfs(int v, int p) {
if (!B[v]) {
dp[v] = 0;
for (int u : adj[v]) {
if (u == p) continue;
dfs(u, v);
dp[v] += dp[u];
}
ans = max(ans, dp[v]);
return;
}
int mx = 0;
dp[v] = -1;
for (int u : adj[v]) {
if (u == p) continue;
dfs(u, v);
dp[v] += dp[u];
mx = max(mx, dp[u]);
}
dp[v] = max(dp[v], 1);
ans = max({ans, mx + 1, dp[v]});
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n;
fill(dp, dp + MAXN, -INF);
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 1; i <= n; i++) {
char c;
cin >> c;
B[i] = (c == '1');
}
dfs(1, 0);
cout << ans << endl;
return 0;
}
