#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long ll;
#define st first
#define nd second
#define f(a, c, b) for (int a = c; b > a; a++)
#define pb push_back
#define all(a) a.begin(), a.end()
#define sz(a) int(a.size())
#define int ll
#define DUZO 1000000000000000000
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vvi = vector<vector<int>>;
vvi g;
vi on;
vi dp;
int wnk = 0;
void dfs_dp(int v, int p) {
for (int u: g[v]) {
if (u == p) continue;
dfs_dp(u, v);
}
if (on[v]) {
dp[v] = 1;
int kand = -1;
for (int u: g[v]) {
if (u == p) continue;
kand += dp[u];
}
wnk = max(wnk, kand);
dp[v] = max(dp[v], kand);
kand =0;
for (int u: g[v]) {
if (u == p) continue;
kand = max(kand, dp[u]);
}
wnk = max(wnk, 1 + kand);
} else {
for (int u: g[v]) {
if (u == p) continue;
dp[v] += dp[u];
}
wnk = max(wnk, dp[v]);
}
}
void solve() {
int n;
cin >> n;
g.resize(n + 1);
f(i, 1, n) {
int u, v;
cin >> u >> v;
g[u].pb(v);
g[v].pb(u);
}
on.resize(n + 1);
f(i, 1, n + 1) {
char c;
cin >> c;
on[i] = c - '0';
}
dp.resize(n + 1);
dfs_dp(1, 0);
cout << wnk << "\n";
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int q = 1;
//cin >> q;
while (q--) solve();
return 0;
}
