#include<bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for(int i=a; i<=b; i++)
#define all(x) x.begin(), x.end()
#define sz(x) (int) x.size()
#define pb push_back
#define f first
#define s second
#define nl '\n'
typedef long long ll;
// #define int ll
typedef vector<int> vi;
typedef pair<int, int> pii;
#define nl '\n'
const int N=5e5;
int n;
vi adj[N];
string on;
int dp[N];
int ans=-1e9;
void dfs(int x, int par){
int mx=0;
for(int k:adj[x]){
if(k==par) continue;
dfs(k, x);
mx=max(mx, dp[k]);
dp[x]+=max(0, dp[k]);
}
if(on[x]=='1') ans=max(ans, mx+1);
ans=max(ans, dp[x]-(on[x]=='1'));
dp[x]=max(dp[x]-(on[x]=='1'), int(on[x]=='1'?1:-1e9));
}
signed main(){
cin.tie(0)->sync_with_stdio(0);
cin >> n;
rep(i,1,n-1){
int u,v; cin >> u >> v;
adj[u].pb(v);
adj[v].pb(u);
}
cin >> on;
on='0'+on;
dfs(1, 0);
cout << ans;
}
