#include <bits/stdc++.h>
using namespace std;
#define ll long long
int sc = 0;
void dfs (int v, vector<vector<int>> &g, vector<bool> &odw, vector<int> &dp, vector<bool> &c) {
odw[v] = 1;
vector<int> x;
int s = 0;
for (int u : g[v]) {
if (!odw[u]) {
dfs(u, g, odw, dp, c);
x.push_back(dp[u]);
s += dp[u];
}
}
if (!c[v]) {
dp[v] = s;
}
else {
if (x.empty()) {
dp[v] = 1;
sc = max(sc, 1);
return;
}
sort(x.begin(), x.end(), greater<int>());
sc = max(sc, x[0]+1);
dp[v] = max(1, s-1);
}
sc = max(sc, dp[v]);
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
vector<vector<int>> g (n+1);
for (int i = 0; i < n-1; i++) {
int a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
string s;
cin >> s;
vector<bool> c (n+1, 0);
for (int i = 0; i < n; i++) {
c[i+1] = (s[i]=='1');
}
vector<bool> odw (n+1, 0);
vector<int> dp (n+1, 0);
dfs(1, g, odw, dp, c);
cout << sc << '\n';
}
