#include <bits/stdc++.h>
using namespace std;
const int lim = 2e5 + 5;
vector<int> edges[lim];
bool gen[lim], vis[lim];
int res[lim];
int ans = 0;
void dfs(int nd = 1) {
// ambil dr child, itu berarti boleh ambil dr semua di sum terus nanti dikurangi 1
// ambil dr skrg doang -> tergantung gen state
vis[nd] = 1;
int sum = 0, mx = 0;
for(auto i : edges[nd]) {
if(!vis[i]) {
dfs(i);
sum += res[i];
mx = max(mx, res[i]);
}
}
if(!gen[nd]) {
// then just merge aja :D
// berarti lgsg get sum from all
res[nd] = sum;
//cout << sum << endl;
}
else {
// kita harus rusak gen ini
// atau buat gen ini as root
// kalo buat gen as root, berarti choose 1 mx trus itu doang yg nyala
// else sum - 1
res[nd] = max(1, sum - 1);
ans = max(ans, mx + 1);
//cout << nd << " " << mx << " " << sum << endl;
}
}
int main() {
int n;
cin >> n;
for(int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
edges[u].push_back(v);
edges[v].push_back(u);
}
string s;
cin >> s;
for(int i = 1; i <= n; ++i)
gen[i] = s[i - 1] == '1';
dfs(1);
int mx = 0;
for(int i = 1; i <= n; ++i)
mx = max(res[i], mx);
cout << max(mx, ans) << endl;
}
