#include "bits/stdc++.h"
using namespace std;
#define pb push_back
#define endl "\n"
#define int long long
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
const int N = 2e5 + 5;
vector<int> v[N];
string s;
int dp[N];
int ans;
void dfs(int c,int p){
int cur=0,sum=0;
for(int x:v[c]){
if(x==p) continue;
dfs(x,c);
cur=max(cur,dp[x]);
sum+=dp[x];
}
if(s[c]=='1'){
ans=max(ans,sum-1);
ans=max(ans,cur+1);
ans=max(ans,1LL);
}
else ans=max(ans,sum);
if(s[c]=='1') dp[c]=max(1LL,sum-1);
else dp[c]=sum;
}
void solve(){
int n;
cin >> n;
for(int i=1;i<n;i++){
int a,b;
cin >> a >> b;
v[a].pb(b);
v[b].pb(a);
}
cin >> s;
s = " " + s;
dfs(1,0);
cout << ans << endl;
}
int32_t main(){
cin.tie(0); ios::sync_with_stdio(0);
int t=1;//cin >> t;
while(t--) solve();
return 0;
}
