#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define all(c) (c).begin(), (c).end()
#define sz(c) (int)(c).size()
#define vt vector
#define pb push_back
#define F first
#define S second
#define pll pair<ll,ll>
#define MP make_pair
const int mxN = 200'001;
vt<int> adj[mxN];
bool power[mxN];
int dp[mxN];
int ans=0;
void dfs(int s, int e) {
if (power[s]){
int cur=0;
for (int u: adj[s]){
if (u == e) continue;
dfs(u, s);
dp[s]+=dp[u];
cur=max(cur,dp[u]+1);
}
ans=max(ans,cur);
dp[s]--;
dp[s]=max(dp[s], 1);
} else {
for (int u: adj[s]){
if (u == e) continue;
dfs(u, s);
dp[s]+=dp[u];
}
ans=max(ans,dp[s]);
}
}
void solve(){
int n; cin>>n;
for (int i=0;i<n-1;i++){
int u,v; cin>>u>>v;
adj[u].pb(v); adj[v].pb(u);
}
string s; cin>>s;
for (int i=1;i<=n;i++) {power[i]=s[i-1]=='1';}
dfs(1, 0);
cout << ans << endl;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
solve();
return 0;
}
