#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 200005;
int n;
string s;
vector<int> adj[N];
int dp[N][2];
void dfs(int u, int p) {
if (s[u] == '0') {
for (int v : adj[u]) {
if (v != p) {
dfs(v, u);
dp[u][0] += dp[v][0];
dp[u][1] = max(dp[u][1], dp[v][1]);
}
}
dp[u][1] = max(dp[u][1], dp[u][0]);
} else {
int sum0 = 0, max0 = 0, sum1 = 0, max1 = 0;
for (int v : adj[u]) {
if (v != p) {
dfs(v, u);
sum0 += dp[v][0]; max0 = max(max0, dp[v][0]);
sum1 += dp[v][1]; max1 = max(max1, dp[v][1]);
}
}
dp[u][0] = max(sum0 - 1, 1);
dp[u][1] = max(max1, max(max0 + 1, dp[u][0]));
}
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n;
for (int i = 1; i < n; i++) {
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
cin >> s; s = " " + s;
dfs(1, 1);
cout << max(dp[1][0], dp[1][1]);
}
