#include <bits/stdc++.h>
using namespace std;
int main() {
cin.tie(0)->sync_with_stdio(0);
int n;
cin >> n;
vector<vector<int>> adj(n);
for (auto i = 0; i < n - 1; ++i) {
int u, v;
cin >> u >> v;
--u, --v;
adj[u].emplace_back(v);
adj[v].emplace_back(u);
}
vector<bool> s(n);
auto ans = 0;
for (auto i = 0; i < n; ++i) {
char c;
cin >> c;
s[i] = (c == '1');
ans += int(s[i]);
}
ans = min(ans, 2);
vector<int> dp(n), sum(n);
auto f = [&](auto self, int u, int p) -> int {
for (auto v : adj[u]) {
if (v != p) {
sum[u] += self(self, v, u);
}
}
dp[u] = (s[u] ? max(sum[u] - 1, 1) : sum[u]);
return dp[u];
};
f(f, 0, 0);
vector<int> dp_reroot(n), sum_reroot(n);
auto f_reroot = [&](auto self, int u, int p) -> void {
if (u == p) {
dp_reroot[u] = dp[u];
sum_reroot[u] = sum[u];
} else {
sum_reroot[u] = sum[u] + (s[p] ? max(sum_reroot[p] - sum[u] - 1, 1)
: sum_reroot[p] - sum[u]);
dp_reroot[u] = (s[u] ? max(sum_reroot[u] - 1, 1) : sum_reroot[u]);
}
for (auto v : adj[u]) {
if (v != p) {
self(self, v, u);
}
}
};
f_reroot(f_reroot, 0, 0);
ans = max(ans, *max_element(begin(dp_reroot), end(dp_reroot)));
cout << ans << "\n";
}
