#include <bits/stdc++.h>
using namespace std;
#define pb(e) push_back(e)
#define mp(a,b) make_pair(a,b)
const int N = 200003;
vector<int> adj[N];
string s;
int ans;
int dfs(int node , int par){
if(s[node-1] == '0'){
int sum = 0;
for(int i : adj[node]){
if(i!=par){
sum += dfs(i,node);
}
}
return sum;
}
int mx = 0;
int sum = 0;
for(int i : adj[node]){
if(i != par){
int x = dfs(i , node);
mx = max(mx , x);
sum += x;
}
}
ans = max(ans , mx + 1);
return max(1 , sum - 1);
}
void solve(){
int n;
cin >> n;
for(int i = 0; i < n-1; i++){
int a , b;
cin >> a >> b;
adj[a].pb(b);
adj[b].pb(a);
}
cin >> s;
ans = 0;
ans = max(ans , dfs(1,1));
cout << ans << '\n';
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
solve();
return 0;
}
