#include <bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 2e5 + 5;
vector<int> g[maxn];
int dp[maxn], ans;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
string s;
void dfs(int u, int pre){
int mx = 0;
for(int v: g[u]){
if(v == pre) continue;
dfs(v, u);
dp[u] += dp[v];
mx = max(mx, dp[v]);
}
if(s[u - 1] == '1') dp[u] = max(dp[u] - 1, 1ll);
ans = max({ans, dp[u], mx + (s[u - 1] == '1')});
}
void solve(){
int n; cin >> n;
for(int i = 1; i <= n - 1; i++){
int u, v; cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
cin >> s;
dfs(rng() % n + 1, 0);
cout << ans;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
solve();
}
