#include "bits/stdc++.h"
using namespace std;
const int N=200001;
int n;
vector<int> adj[N];
int dp[N][2];
int up[N];
string s;
int ans=1;
void dfs(int x, int par){
dp[x][1]=(s[x]=='1'?1:-1e9);
dp[x][0]=(s[x]=='1')*(-1);
for(int k:adj[x]){
if(k==par) continue;
dfs(k, x);
dp[x][0]+=max({0, dp[k][0], dp[k][1]});
if(s[x]=='1' && s[k]=='1') ans=max(ans, 2);
}
// cout << "dp[" << x << "][" << 0 << "] " << dp[x][0] << '\n';
}
void dfs2(int x, int par){
up[x]=max(up[x], 0);
// cout << "up " << x << " " << up[x] << "\n";
int sum=up[x];
for(int k:adj[x]){
if(k==par) continue;
sum+=max({0, dp[k][0], dp[k][1]});
}
for(int k:adj[x]){
if(k==par) continue;
up[k]=max(dp[x][1], (s[x]=='1')*(-1)+sum-max({0, dp[k][0], dp[k][1]}));
dfs2(k, x);
ans=max(ans, dp[k][0]+up[k]);
}
}
int main(){
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for(int i=1; i<n; i++){
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
cin >> s;
s='0'+s;
dfs(1, 0);
dfs2(1, 0);
cout << ans;
}
