#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define ar array
#define pb push_back
#define ln '\n'
#define int long long
using i64 = long long;
template <class F, class _S>
bool chmin(F &u, const _S &v){
bool flag = false;
if ( u > v ){
u = v; flag |= true;
}
return flag;
}
template <class F, class _S>
bool chmax(F &u, const _S &v){
bool flag = false;
if ( u < v ){
u = v; flag |= true;
}
return flag;
}
const int inf = 1e9;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n; cin >> n;
vector <vector<int>> adj(n);
for ( int i = 1; i < n; i++ ){
int u, v; cin >> u >> v;
--u, --v;
adj[u].pb(v);
adj[v].pb(u);
}
string s; cin >> s;
int cnt = 0;
for ( auto &u: s ){
u -= '0';
cnt += 1;
}
vector <int> dp(n);
int ans = 0;
auto dfs = [&](auto dfs, int u, int p) -> void{
int cnt = 0, ma = 0;
for ( auto &v: adj[u] ){
if ( v != p ){
dfs(dfs, v, u);
cnt += dp[v];
chmax(ma, dp[v]);
}
}
if ( s[u] > 0 ){
chmax(ans, max(cnt - 1, ma + 1));
} else{
chmax(ans, cnt);
}
dp[u] = max((int)s[u], cnt - s[u]);
};
dfs(dfs, 0, -1);
cout << ans << ln;
cout << '\n';
}
