#include <iostream>
#include <vector>
using namespace std;
vector<int> nei[1<<18];
int Up[1<<18], dp[1<<18], Ans;
string s;
void dfs0(int u, int p){
for (int i : nei[u]){
if (i == p)
continue;
dfs0(i, u);
dp[u] += dp[i];
if (s[u - 1] == '1')
Ans = max(Ans, dp[i] + 1);
}
dp[u] = max(s[u - 1] - '0', dp[u] - (s[u-1] == '1'));
}
void dfs1(int u, int p, int chSum = 0){
Ans = max(Ans, dp[u] + Up[p]);
for (int i : nei[u])
if (i != p)
chSum += dp[i];
for (int i : nei[u]){
if (i == p)
continue;
chSum -= dp[i];
Up[u] = max(s[u - 1] - '0', chSum + Up[p] - (s[u - 1] == '1'));
dfs1(i, u);
chSum += dp[i];
}
}
signed main(){
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int n;
cin>>n;
for (int i=1, a, b;i<n;i++){
cin>>a>>b;
nei[a].push_back(b);
nei[b].push_back(a);
}
cin>>s;
dfs0(1, 0);
dfs1(1, 0);
cout<<Ans<<'\n';
}
