#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);
auto f = [&](auto self, int u, int p) -> int {
auto sum = 0;
for (auto v : adj[u]) {
if (v != p) {
sum += self(self, v, u);
}
}
return (s[u] ? max(sum - 1, 1) : sum);
};
for (auto i = 0; i < n; ++i) {
ans = max(ans, f(f, i, i));
}
cout << ans << "\n";
}
