#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int , int> pii;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxn = 2e5 + 10;
const ll mod = 1e9+7;
#define pb push_back
#define endl '\n'
#define dokme(x) cout << x , exit(0)
#define ms(x , y) memset(x , y , sizeof x)
ll pw(ll a, ll b, ll md = mod){ll res = 1;while(b){if(b&1){res=(a*res)%md;}a=(a*a)%md;b>>=1;}return(res);}
int n;
string s;
vector < int > adj[maxn];
int dfs(int v , int par){
int res = 0;
for(int u : adj[v])if(u ^ par)
res += dfs(u , v);
if(s[v] == '1')
res = max(res - 1 , 1);
return res;
}
int solve(int v){
int res = 0;
for(auto u : adj[v])
res = max(res , dfs(u , v));
return res + 1;
}
int32_t main(){
ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
cin >> n;
for(int i = 1 ; i < n ; i ++){
int u , v;
cin >> u >> v;
u -- , v --;
adj[u].pb(v);
adj[v].pb(u);
}
cin >> s;
int ans = 0;
for(int i = 0 ; i < n ; i ++)if(s[i] == '1')
ans = max(ans , solve(i));
cout << ans;
return(0);
}
