#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define MAXN (200005)
vector<ll> v[MAXN];
bool generator[MAXN];
ll dp[MAXN];
ll ans = 0;
void dfs(ll x,ll p){
ll maximum = 0;
ll sum = 0;
for(auto u : v[x]){
if(u != p){
dfs(u,x);
maximum = max(maximum,dp[u]);
sum += dp[u];
}
}
if(generator[x]){
dp[x] = max(1ll,sum - generator[x]);
}else{
dp[x] = sum - generator[x];
}
ans = max(ans,dp[x]);
ans = max(ans,maximum + generator[x]);
}
int main(){
ios_base::sync_with_stdio(false);cin.tie(0);
ll N;
cin>>N;
for(ll i = 0;i < N - 1;i++){
ll a,b;
cin>>a>>b;
a--;
b--;
v[a].push_back(b);
v[b].push_back(a);
}
string s;
cin>>s;
for(ll i = 0;i < N;i++){
if(s[i] == '0') generator[i] = 0;
else generator[i] = 1;
}
dfs(0,-1);
cout<<ans<<'\n';
}
