#include <bits/stdc++.h>
#include <ext/rope>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#define int long long
#define pb push_back
#define x first
#define y second
#define mk(a,b) make_pair(a,b)
#define rr return 0
#define sqr(a) ((a)*(a))
#define all(a) (a).begin(), (a).end()
#define sz(a) (int)(a).size()
using namespace std;
using namespace __gnu_cxx;
using namespace __gnu_pbds;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template<class value, class cmp = less<value> >
using ordered_set = tree<value, null_type, cmp, rb_tree_tag, tree_order_statistics_node_update>;
template<class value, class cmp = less_equal<value> >
using ordered_multiset = tree<value, null_type, cmp, rb_tree_tag, tree_order_statistics_node_update>;
template<class key, class value, class cmp = less<key> >
using ordered_map = tree<key, value, cmp, rb_tree_tag, tree_order_statistics_node_update>;
/// find_by_order()
/// order_of_key()
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
inline int randll(int l = INT_MIN, int r = INT_MAX) {
return uniform_int_distribution<int>(l, r)(rng);
}
const int INF = 1e9, MOD = 1e9 + 7; /// think
const ll LINF = 1e18;
const int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0};
inline bool inside (int x, int y, int n, int m) {
return 0 <= x && 0 <= y && x < n && y < m;
}
template<class T> bool umin (T &a, T b) {return a > b ? (a = b, true) : false; }
template<class T> bool umax (T &a, T b) {return a < b ? (a = b, true) : false; }
vector <vector <int> > edge;
string s;
vector <int> dp[2];
inline void dfs (int v, int p = -1) {
dp[0][v] = s[v] == '1';
dp[1][v] = 0;
int sum = 0;
for (int to : edge[v]) {
if (to != p) {
dfs(to, v);
umax(dp[1][v], dp[1][to]);
if (s[v] == '1') {
umax(dp[1][v], dp[0][to] + 1);
}
sum += dp[0][to];
}
}
umax(dp[0][v], sum - bool(s[v] == '1'));
}
main()
{
ios::sync_with_stdio(0);
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n;
cin >> n;
edge.resize(n);
dp[0].resize(n);
dp[1].resize(n);
for (int i = 1, a, b; i < n; i++) {
cin >> a >> b;
--a, --b;
edge[a].pb(b);
edge[b].pb(a);
}
cin >> s;
dfs(0);
cout << max(dp[0][0], dp[1][0]) << '\n';
}
