#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pb(e) push_back(e)
#define sv(a) sort(a.begin(),a.end())
#define sa(a,n) sort(a,a+n)
#define mp(a,b) make_pair(a,b)
#define vf first
#define vs second
#define ar array
#define all(x) x.begin(),x.end()
const int inf = 0x3f3f3f3f;
const int mod = 1000000007;
const double PI=3.14159265358979323846264338327950288419716939937510582097494459230;
bool remender(ll a , ll b){return a%b;}
//freopen("problemname.in", "r", stdin);
//freopen("problemname.out", "w", stdout);
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);
//int t;cin >> t;while(t--)
solve();
return 0;
}
