#include <cstdio>
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
int n;
vector<int> graph[200005];
string s;
int dp[200005];
int sum[200005];
void predfs(int nod,int tata){
for(auto it:graph[nod]){
if(it == tata){
continue;
}
predfs(it,nod);
sum[nod] += dp[it];
}
if(s[nod] == '1'){
dp[nod] = max(1,sum[nod] - 1);
}
else{
dp[nod] = sum[nod];
}
}
int ans = 0;
void dfs(int nod,int tata){
ans = max(ans,dp[nod]);
for(auto it:graph[nod]){
ans = max(ans,dp[it] + (s[nod] == '1'));
}
for(auto it:graph[nod]){
if(it == tata){
continue;
}
sum[nod] -= dp[it];
if(s[nod] == '1'){
dp[nod] = max(1,sum[nod] - 1);
}
else{
dp[nod] = sum[nod];
}
sum[it] += dp[nod];
if(s[it] == '1'){
dp[it] = max(1,sum[it] - 1);
}
else{
dp[it] = sum[it];
}
dfs(it,nod);
sum[it] -= dp[nod];
if(s[it] == '1'){
dp[it] = max(1,sum[it] - 1);
}
else{
dp[it] = sum[it];
}
sum[nod] += dp[it];
if(s[nod] == '1'){
dp[nod] = max(1,sum[nod] - 1);
}
else{
dp[nod] = sum[nod];
}
}
}
int main(){
cin >> n;
for(int i = 1;i < n;i++){
int x,y;
cin >> x >> y;
graph[x].push_back(y);
graph[y].push_back(x);
}
cin >> s;
s = " " + s;
predfs(1,0);
dfs(1,0);
cout << ans << "\n";
return 0;
}
