#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif
const int N = 2e5 + 5;
int n;
char s[N];
int dp[N], sum[N], f[N], mx[N];
vector<int> g[N];
void dfs(int u, int p) {
for (int v : g[u]) {
if (v != p) {
dfs(v, u);
mx[u] = max(mx[u], dp[v]);
sum[u] += dp[v];
}
}
if (s[u] == '1') {
dp[u] = max(1, sum[u] - 1);
} else {
dp[u] = sum[u];
}
}
int res = 0;
void reroot(int u, int p) {
if (s[u] == '1') {
res = max({res, f[u] + sum[u] - 1, max(f[u], mx[u]) + 1});
}
for (int v : g[u]) {
if (v != p) {
if (s[u] == '1') {
f[v] = max(1, sum[u] - dp[v] + f[u] - 1);
} else {
f[v] = sum[u] - dp[v] + f[u];
}
reroot(v, u);
}
}
}
int main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
cin >> n;
for (int i = 1; i < n; ++i) {
int u, v; cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
for (int i = 1; i <= n; ++i) {
cin >> s[i];
}
dfs(1, 1);
reroot(1, 1);
cout << res;
return 0;
}
