#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define int long long
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define ppb pop_back
#define eb emplace_back
#define g0(a) get<0>(a)
#define g1(a) get<1>(a)
#define g2(a) get<2>(a)
#define g3(a) get<3>(a)
#define g4(a) get<4>(a)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using db = double;
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using iii = tuple<int, int, int>;
using iiii = tuple<int, int, int, int>;
using iiiii = tuple<int, int, int, int, int>;
template<class key, class value = null_type, class cmp = less<key> >
using ordered_set = tree<key, value, cmp, rb_tree_tag, tree_order_statistics_node_update>;
int N, mem[200005][2];
char c;
bool S[200005];
vector<int> adj[200005];
int dp(int n, bool b, int e = -1) {
if (mem[n][b] != -1) return mem[n][b];
if (S[n]) {
if (b) {
int x = -1;
for (auto u : adj[n]) if (u != e) {
x += dp(u, 1, n);
}
return mem[n][b] = max(x, 1ll);
} else {
int x = 0, y = 0, z = 0;
for (auto u : adj[n]) if (u != e) {
x = max(x, dp(u, 1, n));
y += dp(u, 1, n);
z = max(z, dp(u, 0, n));
}
x++;
y--;
return mem[n][b] = max({x, y, z});
}
} else {
if (b) {
int x = 0;
for (auto u : adj[n]) if (u != e) {
x += dp(u, 1, n);
}
return mem[n][b] = max(x, 0ll);
} else {
int x = 0, y = 0, z = 0;
for (auto u : adj[n]) if (u != e) {
x = max(x, dp(u, 1, n));
y += dp(u, 1, n);
z = max(z, dp(u, 0, n));
}
return mem[n][b] = max({x, y, z});
}
}
}
main() {
memset(mem, -1, sizeof mem);
ios::sync_with_stdio(0);
cin.tie(0);
cin >> N;
for (int u, v, i = 1; i < N; i++) {
cin >> u >> v;
adj[u].pb(v);
adj[v].pb(u);
}
for (int i = 1; i <= N; i++) {
cin >> c;
S[i] = (c == '1');
}
cout << dp(1, 0) << '\n';
}
