/* Author : Mychecksdead */
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define pb push_back
#define all(x) x.begin(), x.end()
#define en cout << '\n'
#define ff first
#define ss second
#define pii pair<int,int>
#define vi vector<int>
const int N = 1e6+100, M = 1e5+10, K = 52, MX = 30;
int n, ans = 0, dp[N];
vi g[N];
string s;
void dfs(int v, int p){
int sum = 0;
for(int u: g[v]){
if(u != p){
dfs(u, v);
sum += dp[u];
}
}
if(s[v-1] == '0'){
dp[v] = sum;
}else{
dp[v] = max(1, sum-1);
}
if(p != v){
ans = max(ans, dp[v] + (s[p-1]=='1'));
}
}
void solve(){
cin >> n;
for(int i = 1, u, v; i < n; ++i){
cin >> u >> v;
g[u].pb(v);
g[v].pb(u);
}
cin >> s;
dfs(1, 1);
cout << ans;
}
int main(){
cin.tie(0); ios::sync_with_stdio(0);
int tt = 1, aa;
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
while(tt--){
solve();
en;
}
cerr<<"time taken : "<<(float)clock()/CLOCKS_PER_SEC<<" seconds\n";
return 0;
}
