#include<bits/stdc++.h>
#include<fstream>
using namespace std;
#define sz(a) (int)a.size()
#define ALL(v) v.begin(), v.end()
#define ALLR(v) v.rbegin(), v.rend()
#define ll long long
#define pb push_back
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define ld long double
#define vt vector
#include<fstream>
#define fi first
#define se second
#define pll pair<ll, ll>
#define pii pair<int, int>
#define mpp make_pair
const ld PI = 3.14159265359, prec = 1e-9;;
using u128 = __uint128_t;
//const int x[4] = {1, 0, -1, 0};
//const int y[4] = {0, -1, 0, 1};
const ll mod = 1e6 + 3;
const int mxn = 2e6 + 69, mxq = 1e5 + 5, sq = 500, mxv = 1e6 + 5;
//const int base = (1 <<18);
const ll inf = 1e9 + 5, neg = -69420;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
//const int x[9] = {0, 1, 1, -1, -1, 2, -2, 2, -2};
//const inty[9] = {0, 2, -2, 2, -2, 1, 1, -1, -1};
int n;
vt<int>adj[mxn + 1];
int dp[mxn + 1], sm[mxn + 1], ans = 0;
bool good[mxn + 1];
void dfs(int s, int pre){
int mx = 0;
for(auto i: adj[s]){
if(i != pre){
dfs(i, s); dp[s] += dp[i]; mx = max(mx, dp[i]);
}
}
if(good[s]){
dp[s] = max(dp[s] - 1, 1);
mx++;
}
ans = max(ans, max(dp[s], mx));
//cout << s << " " << dp[s] << "\n";
}
void solve(){
cin >> n;
for(int i = 1; i < n; i++){
int u, v; cin >> u >> v;
adj[u].pb(v); adj[v].pb(u);
}
for(int i = 1; i <= n; i++){
char c; cin >> c;
good[i] = (c - '0');
}
dfs(1, -1);
cout << ans;
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//freopen("COLLEGE.INP", "r", stdin);
//freopen("COLLEGE.OUT", "w", stdout);
int tt; tt = 1;
while(tt--){
solve();
}
return(0);
}
