#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) begin(a),end(a)
const int N = (int)2e5+2;
int n;
string gen;
vector<int> adj[N];
int dp[N], ans;
int dfs(int s, int p){
vector<int> v; v.clear();
for(auto u : adj[s]){
if(u==p) continue;
dfs(u,s); v.pb(dp[u]);
}
int sum = 0, best = 0, ok = (gen[s]=='1');
for(auto u : v) sum+=u, best=max(best,u);
ans = max({ans, sum-ok, best+ok});
dp[s] = max(ok,sum-ok); return ans;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n;
for(int i = 1; i < n; i++){
int a, b; cin >> a >> b;
adj[a].pb(b), adj[b].pb(a);
}
cin >> gen; gen='$'+gen;
cout << dfs(1,-1) << "\n";
}
