#include <bits/stdc++.h>
using namespace std;
int n;
vector<vector<int>> g;
string s;
long long ans = 0;
vector<long long> f;
void dfs(int u, int p) {
for (int v : g[u]) if (v != p) dfs(v, u);
long long mx = 0;
for (int v : g[u]) if (v != p) { f[u] += f[v]; mx = max(mx, f[v]); }
if (s[u] == '1') {
ans = max(ans, mx + 1);
f[u]--;
ans = max(ans, f[u]);
if (f[u] < 1) f[u] = 1;
}
ans = max(ans, f[u]);
}
int main() {
// freopen("main.in", "r", stdin);
// freopen(".out", "w", stdout);
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
g.assign(n + 1, {});
for (int i = 0; i < n - 1; i++) {
int u, v; cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
cin >> s;
s = " " + s;
f.assign(n + 1, 0);
dfs(1, 0);
cout << ans << endl;
}
