#include <bits/stdc++.h>
#define int long long
using namespace std;
const int maxn = 2e5 + 10;
int n;
vector <int> adj[maxn];
string s;
void read (){
cin >> n;
for (int x, y, i = 0; i < n - 1; i++){
cin >> x >> y;
adj[x].push_back(y);
adj[y].push_back(x);
}
cin >> s;
}
int ans, dp[maxn];
void dfs (int v = 1, int p = 0){
int sum = 0;
for (auto u : adj[v]){
if (u == p) continue;
dfs(u, v);
if (s[v - 1] == '1')
ans = max(ans, dp[u] + 1);
sum += dp[u];
}
dp[v] = max(sum - (s[v - 1] == '1' && sum > 0), (int)(s[v - 1] == '1'));
ans = max(ans, dp[v]);
// cout << v << " " << dp[v] << '\n';
}
void solve (){
dfs();
}
void print (){
if (s != string(n, '0'))
ans = max(ans, 1ll);
cout << ans;
}
int32_t main (){
ios_base::sync_with_stdio(0), cin.tie(0);
read();
solve();
print();
}
