//#pragma optimize("Ofast")
//#pragma optimize("unroll-loops")
//#pragma traget("avx,avx2")
#include <iostream>
#include <cmath>
#include <algorithm>
#include <stdio.h>
#include <cstdint>
#include <cstring>
#include <string>
#include <cstdlib>
#include <vector>
#include <bitset>
#include <map>
#include <queue>
#include <ctime>
#include <stack>
#include <set>
#include <list>
#include <random>
#include <deque>
#include <functional>
#include <iomanip>
#include <sstream>
#include <fstream>
#include <complex>
#include <numeric>
#include <cassert>
#include <array>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <thread>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define el '\n'
#define ff first
#define ss second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define point pair <ll, ll>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
using namespace std;
#include <random>
mt19937 rnd(time(0));
const ll INF = 1e18 + 10;
const ll inf = 1e9 + 10;
const ll N = 2e5 + 10;
const ll mod = 1e9 + 7;
const ll K = 7e6 + 100;
const ll LOG = 20;
vector <ll> gr[N];
string s;
ll dp[N], ans = 1;
void dfs(ll v, ll pr) {
if (s[v] == '1')
dp[v] = 1;
ll sum = 0, mx = 0;
for (ll to : gr[v]) {
if (to == pr)
continue;
dfs(to, v);
sum += dp[to];
mx = max(mx, dp[to]);
}
if (s[v] == '1')
sum--, ans = max(ans, mx + 1);
dp[v] = max(dp[v], sum);
ans = max(ans, dp[v]);
}
void solve() {
ll n;
cin >> n;
for (ll i = 1; i < n; i++) {
ll u, v;
cin >> u >> v;
gr[u].pb(v);
gr[v].pb(u);
}
cin >> s;
s = '#' + s;
dfs(1, 1);
cout << ans << el;
return;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int tests = 1;
//cin >> tests;
while (tests--)
solve();
return 0;
}
/*
*/
