#include <bits/stdc++.h>
using namespace std;
int N;
vector<int> graph[200005];
int dp[200005];
string s;
int ans = 0;
void dfs(int n, int p){
int mx = 0;
for(int e : graph[n]){
if(e != p){
dfs(e, n);
dp[n] += dp[e];
mx = max(mx, dp[e]);
}
}
if(s[n-1] == '1'){
dp[n] = max(1, dp[n] - 1);
ans = max(ans, mx + 1);
}
ans = max(ans, dp[n]);
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> N;
for(int i = 1; i<N; i++){
int a, b;
cin >> a >> b;
graph[a].push_back(b);
graph[b].push_back(a);
}
cin >> s;
dfs(1, 0);
cout << max(ans, *max_element(dp+1, dp+1+N)) << "\n";
}
